Progress 10/01/00 to 09/30/05
Outputs
The long term goal of this project was to focus on understanding how M. xanthus recognized starvation and utilize various nutrients. During this granting period we have focused on 1) role of omega-4469 and determined its role in nutrient sensing; and 2) the role of early developmental mutant on their ability to "predate" or utilize other soil bacteria and fungi as sole sources of nutrients. We development a novel predation assay and determined the role of several developmental and motility mutants on predation. We have entered into collaboration with the USDA/ARS to further these studies in the field.
Impacts
These bacteria produce many antimicrobials including antifungals and antibacterials. These compounds are presumed to be used as predation agents, to kill and digest prey organisms. Many of these are controlled by the same regulators that regulate the developmental program. Our work has demonstrated a clear connection between stationary phase, development and predation. In addition this work has aided in our understanding as to how cells regulate the production of these economically and agriculturally important compounds.
Publications
- Pham, V.D., C.W. Shebelut, M. E. Diodati, C.T. Bull and M. Singer. Mutations Affecting Predation Ability of the Soil Bacterium Myxococcus xanthus. 2005. Microbiol. 151:1865-74
- Pham, V.D., C.W. Shebelut, B. Mukherjee, and M. Singer. RasA is Required for Myxococcus xanthus Development and Social Motility. 2005. J. Bacteriol. 187(19):6845-6848
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Progress 01/01/04 to 12/31/04
Outputs
During this period we have focused on the role early developmental mutants and their ability to "predate" or utilize soil bacteria and fungi as sole sources of nutrition. We have demonstrated that many of the early developmental mutants and mutants defective in antimicrobial production are blocked in their ability to act as predators in vitro.
Impacts
These bacteria produce many antimicrobials, during the transition from vegetative growth to development. Our goal is to understand how to increase and optimize production of these antimicrobials and to determine what role they are playing in nature. Understanding the process by which cells sense and respond to nutrients will lead to a better understanding of how cells regulate the production of these economically important compounds.
Publications
- Brenner, M. A.G. Garza, and M. Singer. (2004). Nsd, a locus that affects the Myxococcus xanthus cellular response to nutrient concentration. J. Bacteriol, 186:3461-3471
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Progress 01/01/03 to 12/31/03
Outputs
During this period we have focused on the role of omega-4469 and its role in nutrient sensing. We have renamed the locus, nsd, for nutrient sensing/utilization deficient. We have demonstrated that nsd mutants are unable to grow at low nutrient levels and initiate the developmental program prematurely. In addition, nsd mutants have a 2-fold higher level of the starvation signal (p)ppGpp.
Impacts
These bacteria produce many antimicrobials, during the transition from vegetative growth to development. Our goal is to understand how to increase and optimize production of these antimicrobials. Understanding the process by which cells sense and respond to nutrients will lead to a better understanding of how cells regulate the production of these economically important compounds.
Publications
- No publications reported this period
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Progress 01/01/02 to 12/31/02
Outputs
During this period we have focused on the role of omega-4469 on nutrient sensing. We have determined that this gene product is involved in maintaining proper nutrient levels in cells. Mutations in this gene, cause cells to grow to lower yields and enter the developmental program prematurely. We are currently examining the role of a suppressor, gem-1, a Tup1 homologue, in nutrient sensing.
Impacts
These bacteria produce many antimicrobials, during the transition of vegetative growth to development. Our goal remains to understand how to increase and optimize production. Understanding the process by which cells sense and respond to nutrients will lead to a better understanding of how cells regulate the production of these economically important compounds.
Publications
- No publications reported this period
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Progress 01/01/01 to 12/31/01
Outputs
During this granting period we have continued to work on the regulation of the omega-4469 gene by characterizing its promoter. This gene is being used as a representative of early developmental promoters. We have isolated and mapped 12 suppressors and are focusing our attention on a tup1 homologues to Yeast. We are currently using yeast 2-hybrid methods to identify interacting proteins from M. xanthus.
Impacts
These bacteria produce many antimicrobial agents during the transition from vegetative growth to development. Our goal I s to understand how to increase and optimize the expression of these agents for potential medical and agricultural use. This work will eventually help to offset the economic costs of production of such antimicrobial agents.
Publications
- No publications reported this period
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Progress 01/01/00 to 12/31/00
Outputs
During this granting period we have focused on the delineation of the promoter region for the omega-4469 gene. We have identified a 200-bp region required for activation of transcription for this gene. We have also begun to isolate suppressor mutants that effect both positive and negative regulation from this promoter. To date we have isolated and characterized 20 independent mutants that effect expression of omega-4469. We are currently mapping and cloning these suppressor mutants.
Impacts
These bacteria produce many antimicrobial agents during the transition from vegetative growth to their developmental cycle. The goal is to understand how to increase and optimize the expression of these agents for potential medical and agricultural use. These approaches will eventually help to offset the economic costs of production of such antimicrobial agents.
Publications
- No publications reported this period
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Progress 01/01/99 to 12/31/99
Outputs
During this granting period we have continued to work on the regulation of the SdeK, hisdine kinase. We have demonstrated that SdeK is required prior to C-signaling by using Tn5lac transcriptional fusions. In addition we have begun a biochemical approach to identify substrates for the SdeK kinase. Second, we characterized the promoter regulatory region of the asgE operon. We have demonstrated that AsgE is required for A-signaling, and primarily prevents the accumulation of heat stable A-factor. We have also demonstrated that the defect is not simply a lack of proteases, and that heat stable A-factor is much more complex. We are currently focusing our energies on the understanding of the complex regulatory circuitry of this operon and the function of the AsgE gene.
Impacts
(N/A)
Publications
- Garza, A. G., Harris,B.Z., Pollack, J. S., Singer, M. 1999. The asgE locus is required for cell-cell signaling during MYXOCOCCUS XANTHUS development. Accepted Molecular Microbiology.
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Progress 01/01/98 to 12/01/98
Outputs
During this granting period we have continued to work on the regulation of the SdeK, hisdine kinase. We have recently taken a genetic approach to identify the SdeK cognate response regulator. In addition we have begun a biochemical approach to identify substrates for the SdeK kinase. Second, we characterized the promoter regulatory region of the sdeAB operon. We have identified 3 transcriptional start sites and have evidence for at least three promoters. We are currently focusing our energies on the understanding of the complex regulatory circuitry of this operon.
Impacts
(N/A)
Publications
- Garza, A.G., Pollack, J.S., Harris, B.Z., Lee, A. Keseler, I.M., Licking, E.F. and Singer, M. 1998. SdeK is required for early fruiting body development in MYXOCOCCUS XANTHUS. J. Bacteriol.
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Progress 01/01/97 to 12/01/97
Outputs
During this granting period two significant results have been accomplished. First, we now have biochemical evidence that the putative SdeK kinase does in fact have autophosphorylation activity, thus proving it to be a bona fide kinase. Moreover, this result allows us to biochemically probe the starvation signal transduction pathway in order to identify other components of the system. Along with the biochemical approach we are continuing our genetic approach of the system. Second, we have identified and characterized a second locus, designated SDEAB, as being involved in the early decision making process for the initiation of development in M. XANTHUS.
Impacts
(N/A)
Publications
- Harris, B. Z., Kaiser, P. and Singer, M. 1998. The guonosine nucleotide (p)ppGPP initiates development and A-factor production in MYXOCOCCUS XANTHUS. Genes and Development, Accept for pub.
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