Remodeling of the Streptococcus agalactiae transcriptome in response to growth temperature.
BACKGROUND
To act as a commensal bacterium and a pathogen in humans and animals, Streptococcus agalactiae (group B streptococcus, GBS) must be able to monitor and adapt to different environmental conditions. Temperature variation is a one of the most commonly encountered variables.


RESULTS
To understand the extent to which GBS modify gene expression in response to temperatures encountered in the various hosts, we conducted a whole genome transcriptome analysis of organisms grown at 30 degrees C and 40 degrees C. We identified extensive transcriptome remodeling at various stages of growth, especially in the stationary phase (significant transcript changes occurred for 25% of the genes). A large proportion of genes involved in metabolism was up-regulated at 30 degrees C in stationary phase. Conversely, genes up-regulated at 40 degrees C relative to 30 degrees C include those encoding virulence factors such as hemolysins and extracellular secreted proteins with LPXTG motifs. Over-expression of hemolysins was linked to larger zones of hemolysis and enhanced hemolytic activity at 40 degrees C. A key theme identified by our study was that genes involved in purine metabolism and iron acquisition were significantly up-regulated at 40 degrees C.


CONCLUSIONS
Growth of GBS in vitro at different temperatures resulted in extensive remodeling of the transcriptome, including genes encoding proven and putative virulence genes. The data provide extensive new leads for molecular pathogenesis research.
Mereghetti
Laurent
L
Center for Molecular and Translational Human Infectious Diseases Research, The Methodist Hospital Research Institute, Houston, Texas, United States of America.
Sitkiewicz
Izabela
I
Green
Nicole M
NM
Musser
James M
JM
D020816:Amino Acid Motifs; D000818:Animals; D018407:Bacterial Physiological Phenomena; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial; D044404:Genomic Islands; D006460:Hemolysin Proteins / Q000378:metabolism; D006801:Humans; D008957:Models, Genetic; D020411:Oligonucleotide Array Sequence Analysis; D016366:Open Reading Frames; D012333:RNA, Messenger / Q000378:metabolism; D013292:Streptococcus agalactiae / Q000378:metabolism*; D013696:Temperature; D037521:Virulence Factors
D006460:Hemolysin Proteins; D012333:RNA, Messenger; D037521:Virulence Factors