Expression and phase variation of gonococcal P.11 genes in Escherichia coli involves ribosomal frameshifting and slipped‐strand mispairing

Abstract

Expression and phase variation of Neisseria gonorrhoeae P.II genes in Escherichia coli were studied using TnphoA fusions. Fusions were created in the P.IIc gene of N. gonorrhoeae JS3 using lambda TnphoA-1 and were characterized by restriction digestion and dideoxy sequencing. Three fusions were chosen for further study; Tnp7 (fusion junction at mature amino acid 7), Tnp57 (amino acid 57), Tnp66 (amino acid 66). All fusions were in frame with the P.IIc coding sequence but were out of frame with the purported initiation codon. All fusion constructions were shown to phase vary in E. coli in an analogous fashion to that seen in N. gonorrhoeae, i.e. phase changes (in a recA background) at a frequency of c. 10(-3) accompanied by an alteration at the DNA level of the number of coding repeats (CRs). In vitro mutagenesis of the fusion constructions indicated that expression of out of frame P.II genes in E. coli was probably the result of ribosomal frameshifting within the run of 'A' residues immediately preceding the CR region and not due to low-level false initiation at codons other than the ATG initiation codon (as had previously been suggested). The mechanism for P.IIc::phoA phase variation appears to be related to the 'slipped-strand mispairing' mechanism responsible for frameshift mutations in a number of other bacterial genes containing short, direct, tandem repeats.

Immunological and genetic characterization of Borrelia burgdorferi BapA and EppA proteins

“…Analyses of flanking DNA sequences demonstrated that at least two of these strains are only distantly related to each other (see below), indicating that the mutations probably arose independently. A number of other prokaryotes, including Neisseria and Mycoplasma, regulate expression of certain proteins by inactivating their genes through slipped-strand mispairing during replication of repetitive DNA sequences (Belland et al, 1989;Murphy et al, 1989;Yogev et al, 1991). It has been hypothesized that slipped-strand mispairing modulates expression of the antigenic B. burgdorferi VraA lipoprotein , and our results suggest that a similar regulatory process may also be at work in the bapA gene.…”

Two‐dimensional structure of the Opc invasin from Neisseria meningitidis

“…However, unlike Opc, Opa protein expression is regulated at the translational level (Stern et al, 1986;Kawula et al, 1988;Belland et al, 1989). Opa proteins are encoded by a family of opa genes scattered throughout the bacterial genome Bihlmaier et al, 1991), and vary dramatically in sequence, particularly at two cell-surface-exposed hypervariable regions (Connell et al, 1988;Aho et al, 1991).…”

Recombinational reassortment among opa genes from ET-37 complex Neisseria meningitidis isolates of diverse geographical origins

“…gonorrhoeae (James & Swanson, 1978;Swanson et a/., 1988;Jerse et al, 1994). Phase variation (reversible on-off switching) of Opa proteins results from alterations in reading frame caused by changes in the number of pentanucleotide repeats (CTCTT) in the signal-peptideencoding region of opa genes (Stern et al, 1986;Stern & Meyer, 1987;Kawula et al, 1988;Belland et al, 1989Belland et al, , 1997Murphy et al, 1989). Antigenic variation among the Opa proteins of an individual strain is a consequence of alternate expression from multiple opa loci in the bacterial chromosome, encoding proteins with different antigenic characteristics.…”