Disease relevance of psaA

• The mystery of psaA and penicillin tolerance in Streptococcus pneumoniae [1].
• Gene psaA, which encodes the Streptococcus pneumoniae 37-kDa protein, was cloned in Escherichia coli, and its complete nucleotide sequence was determined [2].
• The mutant contained a single insertion within mtuA, a homologue of mtsA and psaA, which encode metal-binding proteins in Streptococcus pyogenes and Streptococcus pneumoniae, respectively [3].
• Diagnosis of pneumococcal pneumonia by psaA PCR analysis of lung aspirates from adult patients in Kenya [4].
• The psaB, psaC and psaA mutants were completely attenuated in systemic, respiratory tract and otitis media infections [5].

High impact information on psaA

• Virulence-associated changes were demonstrated in the attenuated strain with significant downregulation of a previously determined virulence locus, psaB, psaC and psaA [6].
• Defective adhesion and reduced transformation efficiency, as reported previously for a psaA- mutant, were phenotypes shared by psaB-, psaC- and psaD- knockout mutants [7].
• Consistent with these observations, mice with passively or actively acquired antibodies to PspA or type 3 PS were equivalently protected from homologous systemic challenge with type 3 pneumococci, whereas mice with passively or actively acquired antibodies to PsaA or PpmA were not effectively protected [8].
• Mutations in psaA cause deficiencies in growth, virulence, adherence, and the oxidative stress response [9].
• Many lots of pneumococcal vaccines, including the heptavalent conjugate vaccine, were found to elicit small (but variable) antibody responses to PspA, PsaA, or both [10].

Biological context of psaA

• Cloning and nucleotide sequence analysis of psaA, the Streptococcus pneumoniae gene encoding a 37-kilodalton protein homologous to previously reported Streptococcus sp. adhesins [2].
• The two other ORFs identified flank psaA [2].
• In this study, we have shown that psaA and psaD mutants are highly sensitive to oxidative stress, i.e., to superoxide and hydrogen peroxide, which might explain why they are less virulent than the wild-type strain [11].
• In this study, we used a PCR-amplified internal fragment of the psaA gene from S. pneumoniae type 2 strain D39 cloned in pVA891, to direct the construction of D39 derivatives in which the psaA gene had been specifically interrupted, by insertion-duplication mutagenesis [12].
• RsaI restriction of the amplified 16S rRNA gene confirmed the AccuProbe result for all strains, while the result of the psaA-specific PCR was in concordance with encapsulation for all strains [13].

Anatomical context of psaA

• At this time-point, the mRNAs for PspA and PiaA were most abundant in the nasopharynx, whereas no significant difference in gene expression between niches was observed for ply, psaA and cps2A [14].
• We then conducted a comparison between the virulence of the transformation-deficient strains and that of the wild-type strains, via an evaluation of the ability of each strain to adhere to endothelial cells, and also assessed psaA mRNA expression, and the survival of hosts after bacterial challenge [15].
• Paired sera were tested for antibodies to pneumococcal surface adhesin A protein (PsaA, a 37-kDa cell-wall protein) [16].
• We expressed either cell-associated or cell-free nonfusion PsaA polypeptides using two insect cell lines, Spodoptera frugiperda (Sf9) and Trichoplusia ni 5B1-4 (High-Five) [17].

Associations of psaA with chemical compounds

• psaA encodes a 37-kDa pneumococcal lipoprotein which is part of an ABC Mn(II) transport complex [11].
• We found the psaA-specific PCR to be the genotypic technique best suited for the identification of genuine pneumococci and optochin-resistant pneumococci [13].
• Membrane-bound 'hydrophobic rPsaA' (hrPsaA) expressed by either Sf9 or High-Five cells had a molecular mass of approximately 38 kD by SDS-PAGE and partitioned in a Triton X-114 phase, it reacted with both rabbit polyclonal and five monoclonal anti-PsaA antibodies by dot blot or Western blot analysis [17].
• PsaA was released and purified from cells by lysis in the presence of n-laurylsarcosine; this was followed by ammonium sulfate precipitation and subsequent preparative isoelectric focusing [18].

Other interactions of psaA

• Three PCR techniques (amplification of the psaA, ply, and lytA genes) and a commercial kit (AccuProbe [GenProbe, San Diego, Calif.], based on hybridization with the 16S rRNA gene), all four of which claimed to be specific for Streptococcus pneumoniae, were used to identify 49 alpha-hemolytic streptococcal isolates suspected of being pneumococci [13].
• The expression of ply was upregulated threefold at 12 h, and 10-fold at 24 h post-infection; the expression of pspA and psaA was upregulated threefold and fivefold, respectively, at 12 h post-infection [19].

Analytical, diagnostic and therapeutic context of psaA

• Sequence analysis of the psaA gene from D39 indicated significant deviation from that previously published for the homolog from S. pneumoniae R36A [12].
• Sequences of the PCR products from 12 positive samples were identical to the psaA target gene fragment [4].
• The expression of the psa operon was examined in vivo and the virulence of deletion mutants of psaB, psaC, psaA and psaBCA was assessed in four different animal models of infection [5].
• Strains were confirmed to be pneumococci on the basis of bile solubility, and PCR detection or Southern blotting hybridization of lytA and psaA, genes ubiquitous in this species [20].
• Validation of immunoglobulin G enzyme-linked immunosorbent assay for antibodies to pneumococcal surface adhesin A in the diagnosis of pneumococcal pneumonia among adults in Kenya [21].

References