Cyanobacteria perform two fundamental processes which allow life to exist on Earth: the conversion of light energy into chemical energy with the concomitant production of oxygen and the subsequent dark fixation of CO2 into biomass. The long-term objectives of this research program are to develop a detailed understanding of the responses of these important organisms to environmental stresses, including low- temperature-induced stresses, and to understand the role of multiple Group 2 and 3 sigma factors in the required gene regulatory responses. Most of the proposed studies will be performed using Synechococcus sp. PCC 7002, a physiologically well characterized, rapidly growing, transformable, unicellular, marine cyanobacterium. In the next funding period we will complete the overproduction of all sigma factors for antiserum production, and we will continue our biochemical and physiological analyses of mutants lacking specific sigma factors. The antisera will be used to characterize the expression patterns of sigma factor proteins in cells grown in normal batch cultures or under light- dark cycles and in cultures subjected to a variety of environmental stresses. A global transcription mapping method will be used to identify genes whose transcription is regulated by specific sigma factors. These studies should greatly enhance our understanding of transcription regulation in cyanobacteria, which are unusual among eubacteria in possessing multiple Group 2 sigma factors. During the present funding period we showed that cyanobacteria experience N-limitation when grown at low temperatures and that membrane lipid desaturation extends the growth range to lower temperatures by allowing nitrate assimilation to continue at temperatures below 22 degrees C. The rate-limiting step in nitrate assimilation at low temperature will be determined, and we will determine whether other transport functions are functionally impaired at low temperature or when lipid desaturation is reduced. The membrane fluidity of Synechococcus sp. PCC 7942 will be manipulated to test whether an increase in lipid desaturation can improve transport functions at low temperature. Other adaptive changes that allow cyanobacteria to grow at low temperature will be sought. These studies should help to define parameters that limit bacterial growth at low temperature. In the final aim we will complete the characterization of the rapid peroxidative death phenomenon that we discovered in the current funding period. These last studies could explain bloom disappearance in natural populations and could suggest new approaches for the control of problematic or toxic cyanobacteria in water supplies.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM031625-18
Application #
6363224
Study Section
Microbial Physiology and Genetics Subcommittee 2 (MBC)
Program Officer
Anderson, James J
Project Start
1983-03-01
Project End
2003-02-28
Budget Start
2001-03-01
Budget End
2002-02-28
Support Year
18
Fiscal Year
2001
Total Cost
$265,646
Indirect Cost
Name
Pennsylvania State University
Department
Biochemistry
Type
Schools of Arts and Sciences
DUNS #
City
University Park
State
PA
Country
United States
Zip Code
16802
Shen, Gaozhong; Schluchter, Wendy M; Bryant, Donald A (2008) Biogenesis of phycobiliproteins: I. cpcS-I and cpcU mutants of the cyanobacterium Synechococcus sp. PCC 7002 define a heterodimeric phyococyanobilin lyase specific for beta-phycocyanin and allophycocyanin subunits. J Biol Chem 283:7503-12
Saunee, Nicolle A; Williams, Shervonda R; Bryant, Donald A et al. (2008) Biogenesis of phycobiliproteins: II. CpcS-I and CpcU comprise the heterodimeric bilin lyase that attaches phycocyanobilin to CYS-82 OF beta-phycocyanin and CYS-81 of allophycocyanin subunits in Synechococcus sp. PCC 7002. J Biol Chem 283:7513-22
Woodger, Fiona J; Bryant, Donald A; Price, G Dean (2007) Transcriptional regulation of the CO2-concentrating mechanism in a euryhaline, coastal marine cyanobacterium, Synechococcus sp. Strain PCC 7002: role of NdhR/CcmR. J Bacteriol 189:3335-47
Inoue-Sakamoto, Kaori; Gruber, Tanja M; Christensen, Suzanne K et al. (2007) Group 3 sigma factors in the marine cyanobacterium Synechococcus sp. strain PCC 7002 are required for growth at low temperature. J Gen Appl Microbiol 53:89-104
Shen, Gaozhong; Saunee, Nicolle A; Williams, Shervonda R et al. (2006) Identification and characterization of a new class of bilin lyase: the cpcT gene encodes a bilin lyase responsible for attachment of phycocyanobilin to Cys-153 on the beta-subunit of phycocyanin in Synechococcus sp. PCC 7002. J Biol Chem 281:17768-78
Frigaard, Niels-Ulrik; Sakuragi, Yumiko; Bryant, Donald A (2004) Gene inactivation in the cyanobacterium Synechococcus sp. PCC 7002 and the green sulfur bacterium Chlorobium tepidum using in vitro-made DNA constructs and natural transformation. Methods Mol Biol 274:325-40
Wang, Tao; Shen, Gaozhong; Balasubramanian, Ramakrishnan et al. (2004) The sufR gene (sll0088 in Synechocystis sp. strain PCC 6803) functions as a repressor of the sufBCDS operon in iron-sulfur cluster biogenesis in cyanobacteria. J Bacteriol 186:956-67
Yu, Jianping; Shen, Gaozhong; Wang, Tao et al. (2003) Suppressor mutations in the study of photosystem I biogenesis: sll0088 is a previously unidentified gene involved in reaction center accumulation in Synechocystis sp. strain PCC 6803. J Bacteriol 185:3878-87
Gomez-Lojero, Carlos; Perez-Gomez, Bertha; Shen, Gaozhong et al. (2003) Interaction of ferredoxin:NADP+ oxidoreductase with phycobilisomes and phycobilisome substructures of the cyanobacterium Synechococcus sp. strain PCC 7002. Biochemistry 42:13800-11
Huang, Chenhui; Yuan, Xiaolin; Zhao, Jindong et al. (2003) Kinetic analyses of state transitions of the cyanobacterium Synechococcus sp. PCC 7002 and its mutant strains impaired in electron transport. Biochim Biophys Acta 1607:121-30

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