Transcriptional analysis of the hmw gene cluster of Mycoplasma pneumoniae.
Mycoplasma pneumoniae adherence to host cells is a multifactorial process that requires the cytadhesin P1 and additional accessory proteins. The hmw gene cluster consists of the genes p30, hmw3, and hmw1, the products of which are known to be essential for cytadherence, the rpsD gene, and six open reading frames of unknown function. Putative transcriptional terminators flank this locus, raising the possibility that these genes are expressed as a single transcriptional unit. However, S1 nuclease protection and primer extension experiments identified probable transcriptional start sites upstream of the p32, p21, p50, and rpsD genes. Each was preceded at the appropriate spacing by the -10-like sequence TTAAAATT, but the -35 regions were not conserved. Analysis of the M. pneumoniae genome sequence indicated that this promoter-like sequence is found upstream of only a limited number of open reading frames, including the genes for P65 and P200, which are structurally related to HMW1 and HMW3. Promoter deletion studies demonstrated that the promoter-like region upstream of p21 was necessary for the expression of p30 and an hmw3-cat fusion in M. pneumoniae, while deletion of the promoter-like region upstream of p32 had no apparent effect. Analysis by reverse transcription-PCR confirmed transcriptional linkage of all the open reading frames in the hmw gene cluster. Taken together, these findings suggest that the genes of this locus constitute an operon expressed from overlapping transcripts.
Waldo
R H
RH
Department of Microbiology, University of Georgia, Athens, Georgia 30602, USA.
Popham
P L
PL
Romero-Arroyo
C E
CE
Mothershed
E A
EA
Lee
K K
KK
Krause
D C
DC
D018829:Adhesins, Bacterial / Q000235:genetics; D001426:Bacterial Proteins / Q000235:genetics*; D001483:Base Sequence; D015152:Blotting, Northern; D015815:Cell Adhesion Molecules; D002455:Cell Division / Q000187:drug effects; D002701:Chloramphenicol / Q000494:pharmacology; D002874:Chromosome Mapping; D017353:Gene Deletion; D015964:Gene Expression Regulation, Bacterial; D008565:Membrane Proteins / Q000235:genetics*; D009177:Mycoplasma pneumoniae / Q000235:genetics* / Q000254:growth & development; D011401:Promoter Regions, Genetic / Q000235:genetics; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D012329:RNA, Bacterial / Q000032:analysis; D012333:RNA, Messenger / Q000032:analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014158:Transcription, Genetic / Q000235:genetics*
D018829:Adhesins, Bacterial; D001426:Bacterial Proteins; D015815:Cell Adhesion Molecules; C099979:HMW1 protein, Mycoplasma; C117432:HMW2 protein, bacteria; C067481:HMW3 protein, Mycoplasma; D008565:Membrane Proteins; D011500:Protein Synthesis Inhibitors; D012329:RNA, Bacterial; D012333:RNA, Messenger; D002701:Chloramphenicol