title: New insights into the structure of the reaction centre from Blastochloris viridis: evolution in the laboratory.
abstract: Newly determined crystal structures of the photosynthetic RC (reaction centre) from two substrains of the non-sulfur purple bacterium Blastochloris viridis strain DSM 133, together with analysis of their gene sequences, has revealed intraspecies evolutionary changes over a period of 14 years. Over 100 point mutations were identified between these two substrains in the four genes encoding the protein subunits of the RC, of which approximately one-fifth resulted in a total of 16 amino acid changes. The most interesting difference was in the M subunit where the change from a leucine residue to glycine in the carotenoid-binding pocket allowed NS5 (1,2-dihydroneurosporene) to adopt a more sterically favoured conformation, similar to the carotenoid conformation found in other related RCs. The results of the present study, together with a high rate of mutations in laboratory bacterial cultures described recently, suggest that bacteria evolve faster than has been generally recognized. The possibility that amino acid changes occur within protein sequences, without exhibiting any immediately observable phenotype, should be taken into account in studies that involve long-term continuous growth of pure bacterial cultures. The Blc. viridis RC is often studied with sophisticated biophysical techniques and changes such as those described here may well affect their outcome. In other words, there is a danger that laboratory-to-laboratory variation could well be due to different groups not realising that they are actually working with slightly different proteins. A way around this problem is suggested.
authors: WestCHEM, School of Chemistry, College of Science and Engineering, University of Glasgow, Glasgow Biomedical Research Centre, 120 University Place, Glasgow G12 8TA, UK.
authors: Aleksander W
authors: AW
authors: Roszak
authors: Vladimíra
authors: V
authors: Moulisová
authors: Adhie D P
authors: AD
authors: Reksodipuro
authors: Alastair T
authors: AT
authors: Gardiner
authors: Ritsuko
authors: R
authors: Fujii
authors: Hideki
authors: H
authors: Hashimoto
authors: Neil W
authors: NW
authors: Isaacs
authors: Richard J
authors: RJ
authors: Cogdell
mesh_terms: D020561:Alphaproteobacteria / Q000235:genetics; D000595:Amino Acid Sequence; D001483:Base Sequence; D005075:Biological Evolution; D002338:Carotenoids / Q000737:chemistry; D018360:Crystallography, X-Ray; D040961:Genetic Drift; D008968:Molecular Conformation; D008969:Molecular Sequence Data; D045322:Photosynthetic Reaction Center Complex Proteins / Q000737:chemistry / Q000235:genetics*; D017354:Point Mutation
chemical_list: D045322:Photosynthetic Reaction Center Complex Proteins; D002338:Carotenoids