Antibody-Like Phosphorylation Sites in Focus of Statistically Based Bilingual Approach

In accordance with previous reports, the sequences related to phosporylated protein segments occur in conserved variable domains of immunoglobulins including first of all certain N-terminally located segments. Consequently, we look here for the sequences 1) composing human and mouse proteins different from antigen receptors, 2) identical with or highly similar to nucleotide sequence representatives of conserved variable immunoglobulin segments and 3) identical with or closely related to phosphorylation sites. More precisely, we searched for the corresponding actual pairs of DNA and protein sequence segments using five-step bilingual approach employing among others a) different types of BLAST searches, b) two in-principle-different machine-learning methods predicting phosphorylated sites and c) two large databases recording existing phosphorylation sites. The approach identified seven existing phosphorylation sites and thirty-seven related human and mouse segments achieving limits for several predictions or phylogenic parameters. Mostly serines phosporylated with ataxia-telangiectasia-related kinase (involved in regulation of DNA-double-strand-break repair) were indicated or predicted in this study. Hypermutation motifs, located in effective positions of the selected sequence segments, occurred significantly less frequently in transcribed than non-transcribed DNA strands suggesting thus the incidence of mutation events. In addition, marked differences between the numbers and proportions of human and mouse cancer-related sequence items were found in different steps of selection process. The possible role of hypermutation changes within the selected segments and the observed structural relationships are discussed here with respect to DNA damage, carcinogenesis, cancer vaccination, ageing and evolution. Taken together, our data represent additional and sometimes perhaps complementary information to the existing databases of empirically proven phosphorylation sites or pathogenically important spots.

Study of Klebsiella pneumoniae producing extendedspectrum β-lactamases against aminoglycosides

Klebsiella pneumoniae （ K. pneumoniae） is one of the main gmn-negative bacilli in clinical practice. Nosocomial infections caused by K. pneumoniae producing extended-spectrum β-lactamases （ESBLs） are very difficult to treat. This paper investigated the resistant characteristics of K. pneumoniae producing ESBLs and their aminoglycoside-modifying enzyme gene expressions including Nacetyltransferases and O-adenyltransferases. Bacteria identification and ESBLs confirmatory tests were performed by Phoenix^TM-100 system. And minimum inhibitory concentrations （MICs） of gentamicin, amikacin, kanamycin, tobranycin, netilmicin and neomycin in 53 K. pneumoniae isolates were detected by agar dilution. In addition, six aminoglycoside-modifying enzyme genes were amplified by polymerase chain reaction （PCR） and verified by DNA sequencer. It was found that imipenem and meropenem against 120 K. pneumoniae isolates produced powerful antimicrobial activities. The resistant rates of gentamicin and amikacin were 55.0% and 46.7%, respectively. Except neomycin, MIC50 and MIC90 of gentamicin, amikacin, kanamycin, tobramycin and netilmicin in 53 K. pneumoniae were all 〉 128 μg/ml, and the resistant rates were 83.0%, 52.3%, 75.5%, 81.1% and 69.8%, respectively. However, neomycin was only 39.6%. In addition, five modifying enzyme genes, including aac（3）-Ⅰ, aac（3）-Ⅱ, aac（6＇）-Ⅰb, ant（3＂）-Ⅰ, ant（2＂）-Ⅰ genes, were found in 53 isoaltes except aac （6＇）-Ⅱ, and their positive rates were 11.3%, 67.9%, 47.2%, 1.9% and 39.6%, respectively. It was also confirmed by nucleotide sequence analysis that the above resistant genes shared nearly 100% identities with GenBank published genes. The results obtained in the present study indicated that K. pneumoniae producing ESBLs strains are rapidly spreading in our hospital, and their resistance to aminoglycosides may be associated with aminoglycoside-modifying enzyme gene expressions.