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A R Sánchez-Beato

Publications and source records attributed to A R Sánchez-Beato.

4 recordsLinked to original sources
PubMed1998

Molecular characterization of PcpA: a novel choline-binding protein of Streptococcus pneumoniae.

The gene pcpA that encodes a novel pneumococcal choline-binding protein has been cloned and characterized. Northern blot analysis revealed that pcpA is expressed during the exponential phase of growth of pneumococci as a monocistronic transcript of about 2.3 kb. The transcription start site has been located 132 bp upstream of the start codon and the proposed -35 and -10 boxes that are highly similar to those of the typical sigma 70 promoters from Escherichia coli. This gene encodes a putative 79 kDa protein that contains a typical C-terminal choline-binding domain (ChBD). The ChBD of PcpA is built up by 11 identical motifs of 20 amino acids plus a tail of 19 amino acids, which represents the longest ChBD that has been characterized so far. Interestingly, two tandem arrays of five characteristic amphipathic leucine reach repeats (LRRs) of 22-26 amino acids in length have been found in the N-terminal region of PcpA. Since LRRs have been proposed to be involved in protein-protein and protein-lipid interactions our findings suggests a role for PcpA in pneumococcal adhesion.

Amino Acid Sequence↗
PubMed1997

Identification and characterization of IS1381, a new insertion sequence in Streptococcus pneumoniae.

A new insertion sequence (IS1381) was identified in the genome of Streptococcus pneumoniae R6 as an 846-bp segment containing 20-bp terminal inverted repeats and flanked by 7-bp direct repeats. The three sequenced copies of this element have two overlapping open reading frame (ORF) genes named orfA and orfB. However, significant variations between individual copies were found, suggesting that inactivating mutations have occurred in an original single ORF. Accordingly, the consensus IS1381 element derived from the comparison of the three available copies should contain a single ORF sufficient to encode a basic protein of 267 amino acids which exhibited high similarity to the putative transposases of ISL2 from Lactobacillus helveticus and of IS702 from the cyanobacterium Calothrix sp. strain PCC 7601. A minimum of five to seven copies were detected by hybridization experiments in the R6 genome. In remarkable contrast with the two previously reported pneumococcal insertion sequences, several copies of IS1381 have been detected in all of the clinical isolates tested so far. Interestingly, Streptococcus oralis NCTC 11427 (type strain), a close relative of pneumococcus, does not contain this element, but its occurrence in the type strain of Streptococcus mitis (NCTC 12261) suggests that this species has exchanged DNA with S. pneumoniae directly or through an intermediate species.

Amino Acid Sequence↗
PubMed1996

Molecular characterization of a family of choline-binding proteins of Clostridium beijerinckii NCIB 8052. Evolution and gene redundancy in prokaryotic cell.

Three genes homologous to cspA, which encodes the major secretable protein of Clostridium beijerinckii NCIB 8052 have been cloned and sequenced. The Csp proteins showed the typical modular structure of cell-wall associated proteins and, that found in the choline-binding proteins of Streptococcus pneumoniae. The variable number of repeats that constitute the C-terminal choline-binding domain suggests that the csp genes have evolved by deletion-duplication events. Northern blot analysis indicated that under the culture conditions employed only two genes, cspA and cspC, are efficiently expressed and their products are detected in the culture medium. The csp genes are not contiguously located in the chromosome and appear to be expressed independently. Primer extension experiments located a transcription start site 29 bp upstream of the cspA initiation codon. The -10 and -35 promoter regions are closely related to the consensus sequence of Escherichia coli sigma 70 promoters. The cell wall binding capacity of the clostridial proteins, their abundance in the extracellular media, together with the existence of gene redundancy suggest that the Csp proteins should play an important role in the interaction of this microorganism with its surrounding environment.

Amino Acid Sequence↗