摘要:

SummaryErwinia chrysanthemi, a phytopathogenic bacterium, produces a protease inhibitor which is a low‐molecu‐lar‐weight, heat‐stable protein. In addition to its action on the three E. chrysanthemi extracellular proteases A, B and C, it also strongly inhibits the 50 kD extracellu‐lar protease of Serratia marcescens. Its structural gene (inh) was subcloned and expressed in Escher‐ichia coli, in which it encodes an active inhibitor which was purified. The nucleotide sequence of the inh gene shows an open reading frame of 114 codons. The N‐terminal amino acid sequence of the purified inhibi‐tor was also determined. It indicated the existence of an amino‐terminal signal peptide absent from the mature protein. The inhibitor is entirely periplasmic in E. chrysanthemi and partially peri

ISSN:0950-382X    

DOI:10.1111/j.1365-2958.1989.tb00106.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

SummaryStrains ofRhizobium leguminosarumbiovarviciaespecifically make an abundant protein (Rhi) in free‐living culture but not in bacteroids. Genes needed for Rhi synthesis are on a Sym plasmid and here we show that one of these genes,rhiA, is the structural gene that specifies this polypeptide. Transcription ofrhiArequires a regulatory gene,rhiR, located close torhiAand to nod genes involved in nodulation. Mutations inrhiAorrhiRdo not appear to affect symbiotic nitrogen fixation. Transcription ofrhiAis repressed in cells grown in the presence of the flavanone hesperetin or the flavone apigenin, both of which are potent inducers of transcription ofnodgenes. This was deduced from the use ofrhiA‐lacZfusions; however, when the Rhi polypeptide was detected in SDS gels, there was no apparent difference in the intensity of its staining in extracts obtained from cells grown with or without these flavanoidnodgene inducer molecules. However, a mutation in a nodulation gene,nolR, also closely linked to thenodandrhigenes, caused a severe depression in the amount of Rhi (as seen on gels) that was made in cells grown in the presence of inducer flavano

ISSN:0950-382X    

DOI:10.1111/j.1365-2958.1989.tb00107.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

SummaryClinical isolates ofStreptococcus pneumoniaethat have greatly increased levels of resistance to penicillin (>1000‐fold) have been reported from South Africa during the last ten years. Penicillin resistance in these strains is entirely due to the development of penicillin‐binding proteins (PBPs) with decreased affinity for penicillin. We have cloned and sequenced the coding region for the transpeptidase domain of penicillin‐binding protein 2B from three penicillin‐sensitive strains ofS. pneumoniaeand from a penicillin‐resistant South African strain. The amino acid sequences of the transpeptidase domains of PBP2B of the three penicillin‐sensitive strains were identical and there were only between one and four differences in the nucleotide sequences of their coding regions. The corresponding region of the PBP2B gene from the penicillin‐resistant strain differed by 74 nucleotide substitutions which resulted in 17 alterations in the amino acid sequence of PBP2B. The most remarkable alteration that has occurred during the development of the‘penicillin‐resistant’form of PBP2B is the substitution of seven consecutive residues in a region that is predicted to form a loop at the bottom of the peni

ISSN:0950-382X    

DOI:10.1111/j.1365-2958.1989.tb00108.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

SummaryThe nucleotide sequence of a 1689bp fragment of theBacillus subtiiislocus containingptsX(a crr‐like gene),ptsH(coding for HPr), and the 5’‐end ofptsl(coding for Enzyme I) was determined. The deduced amino acid sequences ofptsHand theN‐terminal part ofptslwere compared to those ofStreptococcus faecalisandEscherichia coli.Transcription fusion demonstrated thatptsHlconstitutes an operon. An open reading frame overlapping the main part ofptsHin the opposite sense was shown to be expressedin vivo, using protein fusions with β‐galactosidase. The deduced amino acid sequence ofptsXshowed significant homology with that ofSalmonella typhimuriumglucose‐specific Enzyme III.ptsXwas preceded by an open reading frame whose amino acid sequence showed strong homology with theC‐terminal part ofE.co

ISSN:0950-382X    

DOI:10.1111/j.1365-2958.1989.tb00109.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

SummaryThe nucleotide sequence of aSalmonella typhimuriumDNA segment of 549 base pairs which encompasses the operator‐promoter of theptsoperon, the entirety of theptsHgene, encoding HPr of the phosphotransferase system (PTS), the first 29 nucleotides of theptslgene, encoding Enzyme I of the PTS, and the intercistronic region between theptsHandptslgenes was determined and compared with the corresponding sequence fromEscherichia coli(De Reuseet al., 1985). The two sequences showed 91 % overall identity, with some regions showing sequence conservation and others exhibiting relative divergence. Two open reading frames were identified in both species: one encoded HPr on the ‘sense’ strand (255 nucleotides; 12 nucleotide differences, no amino acid differences); the other, on the anti‐sense strand, consisted of 291 nucleotides (13 nucleotide differences, 13 amino acid differences). While HPr bears a net negative charge, the putative protein encoded by the open reading frame on the anti‐sense strand is strongly basic.Computer analyses of HPr proteins from five different bacterial genera revealed four regions which show strong sequence identity and therefore are presumed to be critical for maintenance of biological activity. Two of these regions were specific to Gram‐positive bacteria. Proposed functions for each of these regions are discussed. Relative evolutionary distances between the HPr proteins were al

ISSN:0950-382X    

DOI:10.1111/j.1365-2958.1989.tb00110.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

SummaryPertussis toxin (PT) is the major virulence factor ofBordetella pertussis.The cloning and nucleotide sequencing of the PT genes fromB. pertussis, Bordetella parapertussisandBordetella bronchisepticahas elucidated the evolution of theBordetellaspecies and allowed considerable advances towards the understanding of their gene expression and the development of safer vaccines against pertussis.

ISSN:0950-382X    

DOI:10.1111/j.1365-2958.1989.tb00111.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY