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1975-1999
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Abstracts 1975-19841. Kaiser D; Dworkin M. (1975) Gene transfer to myxobacterium by Escherichia coli phage P1. Science 187:653-4. (UI: 75102628) Myxococcus xanthus is a bacterium with an interest for studies of development because it has an organized multicellular phase in its life cycle. Bacteriophage Pl can adsorb to M. xanthus and inject its DNA into this organism despite the wide taxonomic gap separating Myxococcus from Escherichia coli, the source of Pl. A specialized transducing derivative of Pl, called PlCM, can carry a gene for chloramphenicol resistance from E. coli into M. xanthus and generate unstable drug-resistant strains.
2. Hodgkin J; Kaiser D. (1977) Cell-to-cell stimulation of movement in nonmotile mutants of Myxococcus. Proc Natl Acad Sci (USA) 74:2938-42.
3. Bretscher AP; Kaiser D. (1978) Nutrition of Myxococcus xanthus, a fruiting myxobacterium. J Bacteriol 133:763-8. (UI: 78109371) The minimal requirements for vegetative growth of Myxococcus xanthus have been sought. Isoleucine, leucine, and valine were required, and vitamin B12 was needed for the synthesis of methionine. Pyruvate was an excellent energy source and an efficient source of cellular carbon. Acetate, aspartate, glutamate, and most tricarboxylic acid cycle intermediates could also be utilized, but were less efficient sources of carbon and energy than was pyruvate. Many mono- and disaccharides were tested, but, in agreement with earlier results, none served as carbon-energy sources. A minimal medium (A1) has been devised that includes the essential amino acids and vitamin B12, with pyruvate and aspartate as carbon-energy sources. In this medium, M. xanthus could propagate indefinitely, and on it vegetative cells formed colonies with greater than 75% efficiency; hence, it is likely that no organic cofactors other than those present in A1 are required in more than trace amounts. 4. Martin S; Sodergren E; Masuda T; Kaiser D. (1978) Systematic isolation of transducing phages for Myxococcus xanthus. Virology 88:44-53. (UI: 78230395) 5. Kaiser D. (1978) Genetics of cell interactions in myxobacteria. Birth Defects Original Article Series, 14:391-9. (UI: 78145023) 6. Hagen DC; Bretscher AP; Kaiser D. (1978) Synergism between morphogenetic mutants of Myxococcus xanthus. Dev Biol 64:284-96. (UI: 78239480)
7. Hodgkin J; Kaiser D. (1979) Genetics of gliding motility in Myxococcus xanthus (Myxobacterales): genes controlling movement of single cells. Mol Gen Genet 171:167-176. M. xanthus is a gliding bacterium whose motility is subject to intercellular control. Strain DK101 of M. xanthus gives rise to 6 distinct types of nomotile mutants and transduction of motility between mutants, mediated by the generalized transducing phage Mx8, identifies the gene loci that underlie the six types. Five of the types, B, C, D, E, and F, are conditional mutants that can be stimulated to move by wild-type cells or by cells of a different mutant type. Mutants of each stimulation type lie in separate and distinct loci, cglB, cglC, cglD, cglE and cglF. The sixth mutant type can stimulate any of the five other types to move, never moves itself, and is produced by mutations in at least 17 loci. 8. Hodgkin J; Kaiser D. (1979) Genetics of gliding motility in Myxococcus xanthus (Myxobacterales): two gene systems control movement. Mol Gen Genet 171:177-191. A large number of motility mutants of the gliding bacterium Myxococcus xanthus have bene isolated and analyzed by transduction. Almost all nonmotile mutants are found to be double mutants. This is explained by the existence of two parallel and almost independent multi-gene systems controlling motility, in which case at least one mutation in each system would be required to eliminate motility. Only one locus, called mgl, has been found to be shared by both systems. Wild type cells move singly and in groups. Single cells move if they carry a complete gene system A, the genes of which are described in the preceding paper. Groups of cells can move if they carry a complete gene system S, but single A-S+ cells do not move. Linkage analysis reveals at least 9 different loci in system S. One class of S- mutants, those mutated in the locus tgl, are conditional mutants which, after contact with tgl+ cells, become temporarily motile as cell groups. Most system A mutations have little effect on fruiting but many system S mutations block it, suggesting that system S plays a role in the fruiting process. 9. Kaiser D. (1979) Social gliding is correlated with the presence of pili in Myxococcus xanthus. Proc Natl Acad Sci (USA) 76:5952-6. (UI: 80101539) Myxococcus xanthus, an organism whose motility involves cell interactions, normally bears pili. Myxococcal pili are found only at cell poles, are less than 10 nm in diameter, and may be longer than a cell. Myxococcus has two basic patterns of cell movement, adventurous (A-motility) and social (S-motility). Pili are found to be completely correlated with the presence of S-motility. (The S-motility pattern has many groups of cells, almost no single cells, and is governed by a set of genes called system S.) On the other hand, A-motility is in dependent of piliation. (The A-motility pattern has many single, isolated cells and it is governed by a second set of genes called system A.) Electron microscopic examination of more than 40 genetically different strains shows that all A+S+ (wild-type) and A-S+ strains have pili, but A+S- and A-S- strains lack them. Mutations in four different loci belonging to system S were tested and were found to stop productions of pili: the loci sg1A, sg1B, sg1G, and tg1. When brought into contact with tg1+ cells, cells of a tg1- strain, which lack pili, become phenotypically S+, produce pili, and become S-motile. Both motility and the production of pili are transient when initiated in this way. Thus it appears that pili permit cells that are close to one another to move. 10. Kaiser D; Manoil C; Dworkin M. (1979) Myxobacteria: cell interactions, genetics, and development. Annual Review of Microbiology 33:595-639. (UI: 80041207)
11. Manoil C; Kaiser D. (1980) Accumulation of guanosine tetraphosphate and guanosine pentaphosphate in Myxococcus xanthus during starvation and myxospore formation. J Bacteriol 141:297-304. (UI: 80115513) Cultures of Myxococcus xanthus develop multicellular fruiting bodies when starved for carbon and nitrogen sources on an agar surface. Under these conditions of severe starvation, cultures rapidly accumulated a compound identified as guanosine tetraphosphate by chromatographic migration of the compound and of its major acid and alkali breakdown products. The accumulation of guanosine tetraphosphate was reduced in the presence of tetracycline, indicating that it may be synthesized by mechanisms similar to those of Escherichia coli. The guanosine tetraphosphate level was also reduced in starved cultures of a mutant unable to fruit normally, although it has been determined whether the defect in guanosine tetraphosphate accumulation is responsible for the inability to fruit. Induction of spores by glycerol addition led to transient increases in both guanosine tetraphosphate and guanosine pentaphosphate at a stage following most cell shortening, but before spores had acquired full refractility. 12. Manoil C; Kaiser D. (1980) Guanosine pentaphosphate and guanosine tetraphosphate accumulation and induction of Myxococcus xanthus fruiting body development. J Bacteriol 141:305-15. (UI: 80115514) Development of multicellular fruiting bodies of Myxococcus xanthus can be induced by limitation of any of a number of different classes of amino acids. Investigated were amino acids that wild-type strains of M. xanthus are unable to synthesize (isoleucine, leucine, and valine), can synthesize at a low rate (phenylalanine), or can normally synthesize at an adequate rate (tryptophan and serine). In general, gradual rather than abrupt starvation for an essential amino acid was required for the induction of fruiting. Perhaps gradual starvation in general minimizes antagonism between amino acids present in the medium, as was documented for valine starvation. The previously reported induction of fruiting by a high concentration of threonine was shown to be specifically reversed by lysine. Threonine addition may starve cells for lysine by feedback inhibition of aspartokinase activity. Starvation for carbon-energy sources or inorganic phosphate also induced fruiting. As in other bacteria, amino acid starvation of M. xanthus leads to increases in cellular guanosine polyphosphate, usually consisting of large increases in the amount of guanosine pentaphosphate with smaller increases in the level of guanosine tetraphosphate. Guanosine polyphosphate accumulation is thus shown to be correlated with nutritional conditions that induce fruiting, and therefore may serve as an intracellular signal to trigger cells to end vegetative growth and initiate fruiting body development. 13. Manoil C; Kaiser D. (1980) Purine-containing compounds, including cyclic adenosine 3',5'-monophosphate, induce fruiting of Myxococcus xanthus by nutritional imbalance. J Bacteriol 141:374-7. (UI: 80115523) Induction of Myxococcus xanthus fruiting by a number of different purine-containing compounds, including cyclic adenosine 3',5'-monophosphate, is defective in a mutant resistant to 2,6-diaminopurine. Furthermore, the purine-induced fruiting of wild-type cultures is uniquely blocked by a low concentration of added glycine. These results imply that different purine-containing compounds induce fruiting through a single mechanism involving nutritional imbalance.
14. Kuner J; Kaiser D. (1981) Introduction of transposon Tn5 into Myxococcus for analysis of developmental and other non-selectable mutants. Proc Natl Acad Sci (USA) 78:425-9. 15. Kuner J; Avery L; Berg DE; Kaiser D. (1981) Uses of transposon Tn5 in the genetic analysis of Myxococcus xanthus. In D. Schlesinger (ed), Microbiology 1981 (ASM), pp.128-132.
16. Kuner JM; Kaiser D. (1982) Fruiting body morphogenesis in submerged cultures of Myxococcus xanthus. J Bacteriol 151:458-61. (UI: 82213716) Induced by starvation, the development of fruiting bodies by Myxococcus xanthus on glass and plastic surfaces under a layer of liquid was followed microscopically. Calcium ions and a neutral pH were required for development of a Myxococcus strain that grew dispersed in liquid culture. Initially asymmetric aggregates later became round, and sporulation followed aggregation. 17. Shimkets LJ; Kaiser D. (1982) Induction of coordinated movement of Myxococcus xanthus cells. J Bacteriol 152:451-61. (UI: 83007040) Rhythmically advancing waves of cells, called ripples, arise spontaneously during the aggregation of Myxococcus xanthus into fruiting bodies. Extracts prepared by washing rippling cells contain a substance that will induce quiescent cells to ripple. Three lines of evidence indicate that murein (peptidoglycan) is the ripple-inducing substance in the extracts. First, ripple-inducing activity is associated with the cell envelope of sonically disrupted M. xanthus cells. Second, whole cells, cell extracts, or purified murein from a variety of different bacteria are capable of inducing ripples. In contrast, extracts prepared from Methanobacterium spp. which contain pseudomurein instead of typical bacterial murein fail to induce ripples. Third, four components of M. xanthus murein, N-acetylglucosamine, N-acetylmuramic acid, diaminopimelate, and D-alanine, are able to induce ripples. Ripples produced by aggregating cells have a wavelength of 45 micrometers and a maximum velocity of 2 micrometers/min. Both of the multigene systems that control gliding motility appear to be required for rippling, and all known mutations at the spoC locus eliminate both rippling and sporulation. 18. Shimkets LJ; Kaiser D. (1982) Murein components rescue developmental sporulation of Myxococcus xanthus. J Bacteriol 152:462-70. (UI: 83007041) Murein (peptidoglycan) components are able to rescue sporulation in certain sporulation-defective mutants of Myxococcus xanthus. N-Acetylglucosamine, N-acetylmuramic acid, diaminopimelic acid, and D-alanine each increase the number of spores produced by SpoC mutants. When all four components are included they have a synergistic effect, raising the number of spores produced by SpoC mutants to the wild-type level. Murein-rescued spores are resistant to heat and sonic oscillation and germinate when plated on a nutrient-rich medium. They appear to be identical to fruiting body spores in their ultrastructure, in their protein composition, and in their resistance to boiling sodium dodecyl sulfate. Murein rescue of sporulation, like fruiting body sporulation, requires high cell density, a low nutrient level, and a solid surface.
19. Shimkets LJ; Gill RE; Kaiser D. (1983) Developmental cell interactions in Myxococcus xanthus and the spoC locus. Proc Natl Acad Sci (USA) 80:1406-10.The product(s) of the Myxococcus xanthus spoC locus is required for two multicellular activities in fruiting body development, rippling and sporulation. Ripples, which are formed early in development, are spatially separated ridges of cells that move synchronously. Myxospores are heat-resistant resting cells that are formed near the end of the developmental process. To investigate the function of spoC, it was cloned in an Escherichia coli plasmid, then transferred to M. xanthus by specialized transduction with coliphage P1. The plasmid, which cannot replicate in M. xanthus, integrated into the M. xanthus chromosome, producing two copies of the spoC locus in tandem. Cells containing one copy of a mutant allele and one copy of the wild-type allele displayed the wild-type phenotype. Cells containing two different mutant allels and one copy of the wild-type allele displayed the wild-type phenotype. Cells containing two different mutant alleles failed to ripple or sporulate, implying that all four independent spoC mutations are in the same gene or unit of transcription. Homozygous mutant duplications arose from constructions in which DNA from a spoC+ donor was transduced into a spoC recipient, or vice versa, at an average frequency of 14%, indicating that gene conversion was a frequent event. 20. LaRossa R; Kuner J; Hagen D; Manoil C; Kaiser D. (1983) Developmental cell interactions of Myxococcus xanthus: analysis of mutants. J Bacteriol 153:1394-404. (UI: 83135591) A set of developmental mutants have been examined that behave as if defective in cellular interactions necessary for the formation of myxospores during fruiting body development. Sporulation is rescued in these mutants if they are mixed with wild-type cells. Complementation experiments with whole cells divide the mutants into four groups (A, B, C, and D). Mutants of group A appear to be less responsive to starvation, a condition that normally initiates development. Mutants of group D respond to starvation but fail to synthesize myxobacterial hemagglutinin, a protein normally synthesized midway in development. Mutants of groups B and C respond to starvation and synthesize hemagglutinin, but they can be distinguished genetically. Group C mutations all map in a single cluster near insertion omega 1519 of transposon Tn5, which is distant from group B mutations. Thus, each group represents a different defect in development. All of the mutants are induced to sporulate by glycerol. Therefore, we argue that sporulation during fruiting body development depends on several prior interactions between cells. 21. Sodergren E; Kaiser D. (1983) Insertions of Tn5 near genes that govern stimulatable cell motility in Myxococcus. J Mol Biol 167:295-310. (UI: 83241755) Insertions of transposon Tn5 were used to examine the genetics of motility mutants in Myxococcus. Fifteen independent insertions of Tn5 were isolated that were linked to seven different loci that govern motility. Among the motility mutants that can be stimulated to move transiently by contact with other cells, a one-to-one correspondence was confirmed between specificity of stimulation and genetic locus. There are six different specificities and six corresponding loci, as if each locus governs a different protein required for gliding motility. 22. Sodergren E; Cheng Y; Avery L; Kaiser D. (1983) Recombination in the vicinity of insertions of transposon Tn5 in Myxococcus xanthus. Genetics 105:281-91. 23. Kaiser D; Crosby C. (1983) Cell movement and its coordination in swarms of Myxococcus xanthus. Cell Motility 3:227-45. 24. Avery L; Kaiser D. (1983) In situ transposon replacement and isolation of a spontaneous tandem genetic duplication. Mol Gen Genet 191:99-109. (UI: 83296981) Using a specialized transducing P1 phage carrying an insertion of Tn5-132, an insertion of Tn5-wt in the chromosome of Myxococcus xanthus, which codes for resistance to kanamycin, can be replaced with one of Tn5-132, which codes for resistance to tetracycline. That Tn5-132 in the daughter is inserted at the same location in the chromosome as Tn5-wt was in the parent was shown by a variety of physical and genetic tests. Southern blot hybridizations of restriction digests of daughter and parent DNAs probed for sequences homologous to Tn5 show that the physical location is the same. When KmR was transduced from the parent to the TcR daughter by the generalized transducing myxophage Mx4 or Mx8, all the transductants were TcS. Likewise, when the daughter was used as donor, TcR transductants of its KmR parent were KmS. Flanking markers that were linked to KmR in the parent were linked to TcR in the daughter. Spontaneous tandem genetic duplications of portions of bacterial chromosomes can be trapped by transducing a selectable marker from a donor to a recipient that has a different selectable marker at the same genetic location and selecting transductants with both markers. Using Tc-replacement, this technique can be applied to any region of the chromosome. We used it to isolate a spontaneous tandem duplication of part of the M. xanthus chromosome. The duplication was characterized by Southern blot hybridizations probed for Tn5-homologous DNA. It was also shown to be unstable by quantitation of loss of drug resistance. Transduction of the novel joint led to reconstruction of the duplication in the recipient strain. All these tests gave results consistent with the proposed structure. The methods described here are applicable to any bacterium into which transposons can be introduced, and for which some means of genetic exchange is available. 25. Avery L; Kaiser D. (1983) Construction of tandem genetic duplications with defined endpoints in Myxococcus xanthus. Mol Gen Genet 191:110-7. (UI: 83296959)
26. Kaiser D. (1984) Genetics of Myxobacteria. In E Rosenberg (ed), Myxobacteria: Development and Cell Interactions (New York: Springer), pp. 163-84. 27. Kroos L; Kaiser D. (1984) Construction of Tn5 lac, a transposon that fuses lacZ expression to exogenous promoters, and its introduction into Myxococcus xanthus. Proc Natl Acad Sci (USA) 81:5816-20. (UI: 85014858) A promoterless trp-lac fusion fragment was inserted near one end of the bacterial transposon Tn5 in the correct orientation to fuse lacZ gene expression to promoters outside Tn5. The resulting transposon, Tn5 lac, retains the kanamycin-resistance gene of Tn5 and transposes in Escherichia coli at 6% the frequency of Tn5 to many different sites in a bacteriophage lambda target. Expression of beta-galactosidase, the product of the lacZ gene, from Tn5 lac insertions in phage lambda depends both on insertion into a transcription unit in the correct orientation and on the regulation of the promoter of the transcription unit, verifying that by transposition Tn5 lac can fuse lacZ expression to outside promoters. An insertion of Tn5 lac in bacteriophage P1 was isolated and used to introduce Tn5 lac into Myxococcus xanthus, a bacterium that undergoes multicellular development. Stable kanamycin-resistant transductants are obtained that contain no P1 DNA sequences but have Tn5 lac inserted at different sites in the Myxococcus chromosome. Individual transductants express different levels of beta-galactosidase. A chromogenic substrate of beta-galactosidase, 5-bromo-4-chloro-3-indolyl beta-D-galactoside, is toxic in Myxococcus when cleaved in large amounts. In principle, Tn5 lac could be used to assay transcription in any bacterium in which Tn5 can transpose and beta-galactosidase can be measured. 28. Kaiser D. (1984) Regulation of multicellular development in Myxobacteria. In Losick and Shapiro (eds.), Microbial Development (Cold Spring Harbor), pp. 197-218.
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