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Cloning and characterization of nif structural and regulatory genes in the purple sulfur bacterium, Halorhodospira halophila

Paper ID Volume ID Publish Year Pages File Format Full-Text
22318 43268 2006 8 PDF Available
Title
Cloning and characterization of nif structural and regulatory genes in the purple sulfur bacterium, Halorhodospira halophila
Abstract

Halorhodospira halophila is a halophilic photosynthetic bacterium classified as a purple sulfur bacterium. We found that H. halophila generates hydrogen gas during photoautotrophic growth as a byproduct of a nitrogenase reaction. In order to consider the applied possibilities of this photobiological hydrogen generation, we cloned and characterized the structural and regulatory genes encoding the nitrogenase, nifH, nifD and nifA, from H. halophila. This is the first description of the nif genes for a purple sulfur bacterium. The amino-acid sequences of NifH and NifD indicated that these proteins are an Fe protein and a part of a MoFe protein, respectively. The important residues are conserved completely. The sequence upstream from the nifH region and sequence similarities of nifH and nifD with those of the other organisms suggest that the regulatory system might be a NifL-NifA system; however, H. halophila lacks nifL. The amino-acid sequence of H. halophila NifA is closer to that of the NifA of the NifL-NifA system than to that of NifA without NifL. H. halophila NifA does not conserve either the residue that interacts with NifL or the important residues involved in NifL-independent regulation. These results suggest the existence of yet another regulatory system, and that the development of functional systems and their molecular counterparts are not necessarily correlated throughout evolution. All of these Nif proteins of H. halophila possess an excess of acidic residues, which acts as a salt-resistant mechanism.

Keywords
nifA; nifH; nifD; nitrogenase; photobiological hydrogen generation; purple sulfur bacteria; Halorhodospira halophila
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Cloning and characterization of nif structural and regulatory genes in the purple sulfur bacterium, Halorhodospira halophila
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Publisher
Database: Elsevier - ScienceDirect
Journal: Journal of Bioscience and Bioengineering - Volume 101, Issue 3, March 2006, Pages 263–270
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us