Identification of competence pheromone responsive genes in Streptococcus pneumoniae by use of DNA microarrays.
Natural genetic transformation in Streptococcus pneumoniae is controlled in part by a quorum-sensing system mediated by a peptide pheromone called competence-stimulating peptide (CSP), which acts to coordinate transient activation of genes required for competence. To characterize the transcriptional response and regulatory events occurring when cells are exposed to competence pheromone, we constructed DNA microarrays and analysed the temporal expression profiles of 1817 among the 2129 unique predicted open reading frames present in the S. pneumoniae TIGR4 genome (84%). After CSP stimulation, responsive genes exhibited four temporally distinct expression profiles: early, late and delayed gene induction, and gene repression. At least eight early genes participate in competence regulation including comX, which encodes an alternative sigma factor. Late genes were dependent on ComX for CSP-induced expression, many playing important roles in transformation. Genes in the delayed class (third temporal wave) appear to be stress related. Genes repressed during the CSP response include ribosomal protein loci and other genes involved in protein synthesis. This study increased the number of identified CSP-responsive genes from approximately 40 to 188. Given the relatively large number of induced genes (6% of the genome), it was of interest to determine which genes provide functions essential to transformation. Many of the induced loci were subjected to gene disruption mutagenesis, allowing us to establish that among 124 CSP-inducible genes, 67 were individually dispensable for transformation, whereas 23 were required for transformation.
Peterson
Scott N
SN
The Pathogen Functional Genomics Resource Center, The Institute for Genomic Research, Rockville, MD 20850, USA.
Sung
Chang Kyoo
CK
Cline
Robin
R
Desai
Bhushan V
BV
Snesrud
Erik C
EC
Luo
Ping
P
Walling
Jennifer
J
Li
Haiying
H
Mintz
Michelle
M
Tsegaye
Getahun
G
Burr
Patrick C
PC
Do
Yu
Y
Ahn
Susie
S
Gilbert
Joseph
J
Fleischmann
Robert D
RD
Morrison
Donald A
DA
D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology / Q000502:physiology*; D004268:DNA-Binding Proteins / Q000494:pharmacology / Q000502:physiology*; D017353:Gene Deletion; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D020411:Oligonucleotide Array Sequence Analysis; D010452:Peptide Biosynthesis / Q000235:genetics / Q000502:physiology; D010675:Pheromones / Q000494:pharmacology / Q000502:physiology; D012329:RNA, Bacterial / Q000032:analysis / Q000235:genetics; D012333:RNA, Messenger / Q000032:analysis / Q000235:genetics; D012269:Ribosomal Proteins / Q000235:genetics / Q000502:physiology; D013296:Streptococcus pneumoniae / Q000235:genetics* / Q000502:physiology*; D013997:Time Factors; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D015533:Transcriptional Activation; D014169:Transformation, Bacterial
D001426:Bacterial Proteins; C061262:ComA protein, Bacteria; C120829:ComX protein, Streptococcus; D004268:DNA-Binding Proteins; D010675:Pheromones; D012329:RNA, Bacterial; D012333:RNA, Messenger; D012269:Ribosomal Proteins; D014157:Transcription Factors