Department of Microbiology and Molecular Genetics
Physiological, biochemical, genetic and genomic analysis of cellular differentiation in filamentous cyanobacteria - Symbiotic interactions. Our experimetnal system is the filamentous cyanobacterium Nostoc punctiforme. N. punctiforme is unique in that, depending on environmental signals, its vegetative cells can differentiate into three distinct and mutually exclusive cell types: nitrogen-fixing heterocysts (when limited for combined nitrogen), spore-like akinetes (when energy stressed), and motile by gliding hormogonium filaments (under conditions both positive and negative for growth). Moreover, N. punctiforme can fix nitrogen in free-living and plant-associated symbiotic growth states. The plant partners span the phylogenetic spectrum from Bryophyte hornworts and liverworts, to Gymnosperm cycads, and the Angiosperm family Gunneraceae. When in symbiotic association, the plant partners control the differentiation and physiological behavior of hormogonia (the infective units) and heterocysts (the functional units). The genome of N. punctiforme, at 9.059 Mbp, is large for a bacterium and is distributed between an 8.23 Mbp circular chromosome and five plasmids ranging from 26 to 354 kbp. We apply biochemical, genetic and genomic (proteomic and transcriptomic) approaches to identify and manipulate the regulatory pathways of free-living and symbiotic cellular differentiation of N. punctiforme.
Grad Group Affiliations
- MIC 120 Microbial Ecology, Spring
- MIC 140 Bacterial Physiology, Fall
- MIC 200A Biology of Prokaryotes, Fall
- 215 Briggs Hall. Office is 209 Briggs Hall http://microbiology.ucdavis.edu/meeks/
- The current members of the laboratory are: Staff Research Associate Elsie Campbell; Graduate Student Harry Christman; Undergraduate Students Linda Espinoza, Lindsay Wallace, Noor Hafizad Mohd Pushiri.
Honors and Awards
- 2003 Darbaker Prize in Phycology, awarded by the Botanical Society of America
- American Society for Microbiology
- Society for General Microbiology
- Phycological Society of America
- 1966 BS Biology Central Washington University
- 1967 MS Biology Central Washington University
- 1972 PhD Biology University of Oregon
Campbell, E.L., M.L. Summers, H. Christman, M.E. Martin and J.C. Meeks. 2007. Global gene expression patterns of Nostoc punctiforme in steady state dinitrogen-grown heterocyst-containing cultures and at single time points during the differentiation of akinetes and hormogonia. J. Bacteriol. 189:5247-5256.
Soule, T., V. Stout, J.C. Meeks and F. Garcia-Pichel. 2007. Molecular genetics and genomic analysis of scytonemin biosynthesis in Nostoc punctiforme ATCC 29133. J. Bacteriol. 189:4465-4472.
Anderson, D.A., E.L. Campbell and J.C. Meeks. 2006. A soluble 3D LC/MS/MS proteome of the filamentous cyanobacterium Nostoc punctiforme. J. Proteome Res. 5:3096-3104.
Meeks, J.C. 2005. Molecular mechanisms in the nitrogen-fixing Nostoc-Bryophyte symbiosis. In: Molecular Basis of Symbiosis, (J. Overmann, ed.), pp. 165-196. Springer, Heidelberg.
Meeks, J.C. 2004. The genome of the cyanobacterium Nostoc punctiforme. What can we learn from it about free-living and symbiotic nitrogen fixation? In: Nitrogen Fixation: 1888-2001. Vol. VI: Genomes and Genomics of Nitrogen-Fixing Organisms, (R. Palacios and W.E. Newton, eds.), pp. 27-70, Kluwer Academic Publishers, Dordrecht, The Netherlands.
Campbell, E.L., F.C.Y. Wong and J.C. Meeks. 2003. DNA binding properties of the HrmR protein of Nostoc punctiforme responsible for transcriptional regulation of genes involved in differentiation of hormogonia. Mol. Microbiol. 47:573-582.
Meeks, J.C. 2003. Symbiotic interactions between Nostoc punctiforme, a multicellular cyanobacterium, and the hornwort Anthoceros punctatus. Symbiosis 34, 55-71.
Wong, F.C.Y. and J.C. Meeks. 2002. Establishment of a functional symbiosis between the cyanobacterium Nostoc punctiforme and the bryophyte Anthoceros punctatus requires genes involved in nitrogen control and initiation of heterocyst differentiation. Microbiology 148:315-323.
Meeks JC and J Elhai. 2002. Regulation of cellular differentiation in filamentous cyanobacteria in free-living and plant-associated symbiotic growth states. Microbiology and Molecular Biology Reviews. 66:94-121
Meeks, J.C., E.L. Campbell, M.L. Summers and F.C. Wong. 2002. Cellular differentiation in the cyanobacterium Nostoc punctiforme. Arch. Microbiol. 178:395-403.
Hagen KD and JC Meeks. 2001. The unique cyanobacterial protein OpcA is an allosteric effector of glucose-6-phosphate dehydrogenase in Nostoc punctiforme ATCC 29133. Journal of Biological Chemistry. 276:11477-11486
Wong, F.C.Y. and J.C. Meeks. 2001. The hetF gene product is essential to heterocyst differentiation and affects HetR function in the cyanobacterium Nostoc punctiforme. J. Bacteriol. 183:2654-2661
Meeks JC, Elhai J, Theil T, Potts M, Larimer F, Lemerdin J, Predki P and R Atlas. 2001. An overview of the genome of Nostoc punctiforme, a multicellular, symbiotic cyanobacterium. Photosynthesis Research. 70:85-106