期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2005
卷号：102
期号：14
页码：5162-5167
DOI：10.1073/pnas.0408536102
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Previous studies have shown that a {sigma}54-{sigma}S cascade regulates the expression of a few key lipoproteins in Borrelia burgdorferi, the agent of Lyme disease. Here, we demonstrate that these sigma factors, both together and independently, regulate a much more extensive number of genes and cellular processes. Microarray analyses of {sigma}54 and {sigma}S mutant strains identified 305 genes regulated by {sigma}54 and 145 regulated by {sigma}S, whereas the {sigma}54-{sigma}S regulatory cascade appears to control 48 genes in B. burgdorferi. In silico analyses revealed that nearly 80% of genes with altered expression in the {sigma}54 mutant were linked to potential {sigma}54-dependent promoters. Many {sigma}54-regulated genes are expressed in vivo, and through genetic complementation of the mutant, we demonstrated that {sigma}54 was required by B. burgdorferi to infect mammals. Surprisingly, {sigma}54 mutants were able to infect Ixodes scapularis ticks and be maintained for at least 24 wk after infection, suggesting the {sigma}54-{sigma}S regulatory network was not involved in long-term survival in ticks. However, {sigma}54 mutants did not enter the salivary glands during tick feeding, indicating that {sigma}54-regulated genes were involved in the transmission process.
