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The study aims to reveal phylogenetic and evolutionary relationship between aerobic anoxygenic phototrophic bacteria (AAnPB) and their relatives, anaerobic anoxygenic phototrophic bacteria (AnAnPB) and nonphototrophic bacteria (NPB, which had high homology of 16S rDNA gene with AAnPB and fell into the same genus), and validate reliability and usefulness of farnesyl pyrophosphate synthase (FPPS) gene for the phylogenetic determination. FPPS genes with our modified primers and 16S rDNA genes with general primers, were amplified and sequenced or retrieved from GenBank database. In contrast to 16S rDNA gene phylogenetic tree, AAnPB were grouped into two clusters and one branch alone with no intermingling with NPB and AnAnPB in the tree constructed on FPPS. One branch of AAnPB, in both trees, was located closer to outgroup species than AnAnPB, which implicated that some AAnPB would be diverged earlier in FPPS evolutionary history than AnAnPB and NPB. Some AAnPB and NPB were closer located in both trees and this suggested that they were the closer relatives than AnAnPB. Combination codon usage in FPPS with phylogenetic analysis, the results indicates that FPPS gene and 16S rRNA gene have similar evolutionary pattern but the former seems to be more reliable and useful in determining the phylogenic and evolutionary relationship between AAnPB and their relatives. This is the first attempt to use a molecular marker beside 16S rRNA gene for studying the phylogeny of AAnPB, and the study may also be helpful in understanding the evolutionary relationship among phototrophic microbes and the trends of photosynthetic genes transfer. [ABSTRACT FROM AUTHOR]

Examines the physiological and ecological features of aerobic anoxygenic phototrophic bacteria (AAPB). Roles of AAPB in the marine ecosystems; Cell division of mother AAPB; Bacteriochlorophyll found in AAPB.

We have investigated the action of seryl-histidine dipeptide (SH)on Green Fluorescent Protein (GFPxm) by SDS-PAGE and fluorescence techniques. It was found that 1 mmol SH showed a 75 units protease K (PK)-like cleavage effect at 50 °C, pH 6.5-7.5. Compared with the results of SH cleavage on BSA, SDS-PAGE experiments showed no obvious fragments resulting from SH cleavage of GFPxm. SH quenched the GFPxm fluorescence greatly prior to cleavage. When the SH concentration reached 150 mM, the fluorescence quenching phenomena stopped. Compared with seryl-histidine dipeptide, the individual amino acids Ser and His, and these two amino acids mixed together, showed no effects on the spectral characteristics of GFPxm nor cleavage of GFPxm. Further study of the SH protein cleavage mechanism might provide insight for protease mechanisms and biomacromolecule evolution. [ABSTRACT FROM AUTHOR]