Roles Of Tricarboxylic Acid Cycle In Staphyloxanthin Production In Staphylococcus Aureus

Staphylococcus aureus is the cause of nosocomial infections and community-acquiredhuman pathogens. Typical of Staphylococcus aureus for the ball,visible under themicroscope arranged in grapes cluster, Therefore be referred to as Staphylococcus. At thesame time, it produces a golden carotenoid and the name of the Staphylococcus aureus.The golden carotenoid pigment (Staphyloxanthin) enhanced bacteria to oxidative stress andneutrophil phagocytosis resistance to the host, can help the bacteria evade the host immunesystem, the virulence of the bacteria are closely linked.In our previous research,we found that the transposon insertion to citrate synthase citZof genes lead to Staphylococcus aureus golden pigment capacity was significantlyenhanced in glucose-free TSB medium,suggesting that of the citric acid cycle of the goldenaureus golden pigment has an important regulatory function.In my research work, the mainresearch contents and results are as follows:1、By molecular cloning, functional complementation confirmed citZ gene mutationsaffect the generation of a golden yellow pigment. Adjust the way, in glucose-free TSBmedium citZ gene negative regulator of the Staphylococcus aureus golden pigmentproduction;TSB medium containing glucose the gene citZ positive regulator ofStaphylococcus aureus gold the production of yellow pigment.2、By molecular cloning, functional complementation, another key gene in the citricacid cycle pathway, citG gene also regulates the generation of the Staphylococcus aureusgolden pigment with citZ gene regulation in a similar way.3、Acetyl coenzyme A content in the detection of Staphylococcus aureus, found inglucose-free TSB medium, citZ gene mutations lead to acetyl coenzyme A accumulation.In glucose-containing culture conditions, citZ gene mutation and did not cause theaccumulation of acetyl coenzyme A;The contrary, compared with the wild type strain, thecitZ gene mutant acetyl coenzyme A content was significantly reduced by about5times.4、Molecular cloning, functional complementation confirmed the mevalonate pathwayispA gene of Staphylococcus aureus golden pigment.5、Using HPLC analysis of metabolites in the mevalonate pathway. Found inglucose-free TSB medium, citZ gene mutations lead to the accumulation of metabolitesrelated to the mevalonate pathway.6、Using gene expression profiling analysis, we found citZ gene mutations affecting the expression of209genes.41genes were upregulated;168genes were downregulated.10transporter-related, and13genes and metabolic genes up-regulated, seven genes withstress-related, four genes with regulatory function related，hypothetical protein of ninegenes,other functions there are five genes; down the genes,35genes are related to thetransporter,14genes are related to toxin expression,18genes are related to fatty acidmetabolism,16genes related to carbohydrate metabolism,5genes are related to glycerolmetabolism the five genes with the citric acid cycle, the two genes are related to ureametabolism, three genes are related to nitrate metabolism, seven genes with regulatoryfunction, nine genes involved in hypothetical protein,three genes for other functions.five genes involved in pigment synthesis in the citric acid cycle.7、The animal infection experiments found a significant reduction in citZ genemutation that causes bacterial pathogenicity.These preliminary findings show that the citric acid cycle by regulating the flow ofacetyl coenzyme A into mevalonate pathway, and then enter the pigment biosyntheticpathway, there by regulating the generation of the golden yellow pigment; and the citricacid cycle and pathogenicity of the bacteria closely related.