Protein repair in non-growing bacteria: implications for bioenergy production
Abstract
Non-growing cells of the phototrophic bacterium Rhodopseudomonas palustris (Rpa1) can survive and produce hydrogen continuously for months as long as they are provided light as an energy source and a suitable electron donor. While this has obvious potential as a means of biofuel production, the genetic and physiological strategies that have evolved in this bacteria for long-term survival in a non-growing state are largely unexplored. Following up on genomic studies of Rpa1 under non-growth conditions, this proposal examines the global role of protein repair and maintenance in maintaining active Rpa1 metabolism in the non-growing state. Specific attention will also be paid to test the hypothesis that specific mechanisms exist for the maintenance and repair of Rpa1 nitrogenase, the enzyme that catalyzes hydrogen production in non-growing cells. From a large-scale transposon mutagenesis screen of Rpa1 cells advancing into a non-growing state, a gene annotated as a protein L-isoaspartate O-methyltransferase (PIMT) involved in protein repair became essential for survival after 14 days of non-growth. It was further determined that while E. coli and mammals have only one PIMT gene, Rpa1 has three. The hypothesis that each of the PIMT enzymes encoded by Rpal are crucial for long-term viability will be tested. The substrate specificities and kinetics of purified Rpal PIMT enzymes will be determined as will the global effects of various comgination of PIMT mutants on cellular integrity furing growth and non-growth. Furthermore, particular attention will be paid to the repair of Rpal nitrogenase, a highly complex multi-subunit enzyme that is very present in very large amounts in Rpal and is responsible for hydrogen gas production.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jan 12, 2017
- Source ID
- W911NF1510150
Entities
People
- Caroline S. Harwood
Organizations
- Army Contracting Command
- United States Army
- University of Washington