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The General Stress Response Factor EcfG Regulates Expression of the C-2 Hopanoid Methylase HpnP in Rhodopseudomonas palustris TIE-1

Kulkarni, Gargi and Wu, Chia-Hung and Newman, Dianne K. (2013) The General Stress Response Factor EcfG Regulates Expression of the C-2 Hopanoid Methylase HpnP in Rhodopseudomonas palustris TIE-1. Journal of Bacteriology, 195 (11). pp. 2490-2498. ISSN 0021-9193. PMCID PMC3676068. http://resolver.caltech.edu/CaltechAUTHORS:20130627-100549056

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Abstract

Lipid molecules preserved in sedimentary rocks facilitate the reconstruction of events that have shaped the evolution of the Earth's biosphere. A key limitation for the interpretation of many of these molecular fossils is that their biological roles are still poorly understood. Here, we use Rhodopseudomonas palustris TIE-1 to identify factors that induce biosynthesis of 2-methyl hopanoids (2-MeBHPs), progenitors of 2-methyl hopanes, one of the most abundant biomarkers in the rock record. This is the first dissection of the regulation of hpnP, the gene encoding the C-2 hopanoid methylase, at the molecular level. We demonstrate that EcfG, the general stress response factor of alphaproteobacteria, regulates expression of hpnP under a variety of challenges, including high temperature, pH stress, and presence of nonionic osmolytes. Although higher hpnP transcription levels did not always result in higher amounts of total methylated hopanoids, the fraction of a particular kind of hopanoid, 2-methyl bacteriohopanetetrol, was consistently higher in the presence of most stressors in the wild type, but not in the ΔecfG mutant, supporting a beneficial role for 2-MeBHPs in stress tolerance. The ΔhpnP mutant, however, did not exhibit a growth defect under the stress conditions tested except in acidic medium. This indicates that the inability to make 2-MeBHPs under most of these conditions can readily be compensated. Although stress is necessary to regulate 2-MeBHP production, the specific conditions under which 2-MeBHP biosynthesis is essential remain to be determined.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1128/JB.00186-13DOIArticle
http://jb.asm.org/content/195/11/2490PublisherArticle
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3676068/PubMed CentralArticle
ORCID:
AuthorORCID
Newman, Dianne K.0000-0003-1647-1918
Additional Information:© 2013 American Society for Microbiology. Received 13 February 2013; Accepted 18 March 2013. Published ahead of print 22 March 2013. This study was supported by awards from NASA (NNX12AD93G) and the Howard Hughes Medical Institute (HHMI) to DKN. DKN is an HHMI Investigator. We thank Tim Donohue for the suggestion to consider ECF sigma factor regulation of hpnP, Maureen Coleman for help with bioinformatic analysis and members of the Newman lab for constructive comments on the manuscript.
Funders:
Funding AgencyGrant Number
NASANNX12AD93G
Howard Hughes Medical Institute (HHMI)UNSPECIFIED
PubMed Central ID:PMC3676068
Record Number:CaltechAUTHORS:20130627-100549056
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20130627-100549056
Official Citation:The General Stress Response Factor EcfG Regulates Expression of the C-2 Hopanoid Methylase HpnP in Rhodopseudomonas palustris TIE-1 Gargi Kulkarni, Chia-Hung Wu, and Dianne K. Newman J. Bacteriol. June 2013 195:11 2490-2498; published ahead of print 22 March 2013, doi:10.1128/JB.00186-13
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:39124
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:02 Jul 2013 23:34
Last Modified:24 Oct 2017 16:20

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