The Comparison Of Lipid Metabolism In Bacterial Genomes

Lipid is a large class of organic compounds in vivo of creature and plays an important role in biological functions. For a long time, researchers have focused on the lipid metabolism of animals mainly through experimental methods while paid less attention to the lipid metabolism of bacteria relatively and most of these researches were limited to analyse a protein or gene which is related to the lipid synthesis and degradation of a single bacterium. In order to solve this problem, we used the methods of genomic analysis to compare the difference including in the pathways of lipid metabolism in different species of bacteria.However, due to the absence of abundant experimental evidence, many problems still existed in the annotations of the sequenced bacterial genomes in current public databases. We completed the re-annotation of the genomes of slected bacteria, and attribute 131 re-annotated bacteria to different classification, in accordence with their gram properties, optimum growth temperature and oxygen demand. We counted up the distribution of lipid metabolizing enzymes in every bacterium on the level of gene and worked out the difference of lipid metabolizing enzymes among different bacteria's genomes.After counting up and analyzing the lipid metabolizing enzymes in bacteria's genomes, we found that the lipid metabolism of different species of bacteria mainly differ as following. (1) Anaerobic bacteria synthesize the unsaturated fatty acid by extending the unsaturated fatty acid chain while the aerobic bacteria synthesize the unsaturated fatty acid through the dehydrogenation of long chain fatty acid. (2) The unsaturated fatty acid synthesis enzymes mainly exist in low and medium temperature bacteria and rarely exist in high temperature bacteria. (3) The 3-keto acyl-ACP synthase III which is responsible for the synthesis of starting fatty acid and the extension of the initial fatty acid chain is widespread in bacteria. However, high temperature bacteria extend the following fatty acid chain mainly depending on 3-keto acyl-ACP synthase II while low and medium bacteria mainly depending on 3-keto acyl-ACP synthaseâ… .(4) Gram-positive bacteria could also synthesize the isopentenyl pyrophosphate by mevalonate pathway that exists in mammals. (5) Bacteria generate phosphatidic acid primarily through glycerol-3-phosphate pathway which exists widely in the genome of bacteria. In theâ…¡-type of fatty acid synthesis pathway of bacteria, every step of the reaction is catalyzed by separate enzyme, and these enzymes have high specificity in different species of bacteria, making relative enzymes of the synthesis of fatty acid in pathogenic bacteria be ideal on selecting targets of antimicrobial drugs. The three-dimensional structure of fatty acid synthesis relative enzymes of three pathogenic bacteria (Streptococcus pneumoniae, Mycobacterium ulcerans, Enterococcus faecalis)were constructed by using homology modeling, which is valuable for developing and selecting antibacterial drugs against these three pathogenic bacteria.