Analysis of APPL1 Gene Polymorphisms in Patients with a Phenotype of Maturity Onset Diabetes of the Young

The APPL1 gene encodes a protein mediating the cross-talk between adiponectin and insulin signaling. Recently, it was found that APPL1 mutations can cause maturity onset diabetes of the young, type 14. Here, an analysis of APPL1 was performed in patients with a maturity-onset diabetes of the young (MODY) phenotype, and prevalence of these mutations was estimated in a Russian population, among type 2 diabetes mellitus (T2DM) and MODY patients. Whole-exome sequencing or targeted sequencing was performed on 151 probands with a MODY phenotype, with subsequent association analysis of one of identified variants, rs11544593, in a white population of Western Siberia (276 control subjects and 169 T2DM patients). Thirteen variants were found in APPL1, three of which (rs79282761, rs138485817, and rs11544593) are located in exons. There were no statistically significant differences in the frequencies of rs11544593 alleles and genotypes between T2DM patients and the general population. In the MODY group, AG rs11544593 genotype carriers were significantly more frequent (AG vs. AA + GG: odds ratio 1.83, confidence interval 1.15–2.90, p = 0.011) compared with the control group. An association of rs11544593 with blood glucose concentration was revealed in the MODY group. The genotyping data suggest that rs11544593 may contribute to carbohydrate metabolism disturbances

Characterization of Streptococcus pneumoniae strains causing invasive infections using whole-genome sequencing

Purpose: antigenic and genetic characterization of Streptococcus pneumoniae strains isolated from patients with invasive forms of pneumococcal infection using whole-genome sequencing.Materials and Methods. The study was performed on 46 S. pneumoniae strains isolated during the PEHASus multicenter studies in 2015-2018. Sequencing was performed using Illumina protocols and equipment. The SPAdes, SeroBA, PneumoCaT software were used for data processing, as well as BIGSdb software (PubMLST.org).Results and Discussion. Whole-genome sequences of strains were obtained; the information was entered into the PubMLST database (id: 51080-51125). Ten (21%) strains were found to have serotype 3. Five (11%) strains belonged to serotype 19F and five to serogroup 6; two of them belonged to serotype 6A; one strain had 6B and 1 had 6BE serotype; 1 strain showed discordant result (6A or 6BE). Serotype 15B was identified in 3 (6.5%) strains. Serotypes 7F, 8, 9V, 14, 22F, 23F and 28A were identified in two strains each; serotypes 1, 4, 9N, 10C, 12F, 18C, 35F, 37 and 38 were found once. The proportion of strains with serotypes included in PCV13 and PPV23 vaccines was 65% and 80%, respectively. 36 sequence types were found in strains; out of them, 6 sequence types were found for the first time. A dominant sequence type or clone complexes could not be identified using multilocus sequence typing except for serotype 3 strains. The inability to identify clonal complexes is in congruence with the previously obtained data on the absence of S. pneumoniae clones associated with pneumococcal meningitis in Russia.Conclusion. The information about serotypes of S. pneumoniae causing invasive infections together with epidemiologic data about strain sources and vaccination allows us to evaluate the effectiveness of pneumococcal vaccines and provide information for improving the PCR-based routine serotyping

The K218 capsular polysaccharide produced by Acinetobacter baumannii isolate 52-249 includes 5,7-di-N-acetylpseudaminic acid linked by a KpsS3 glycosyltransferase

Two acylated forms of the higher sugar, 5,7-diamino-3,5,7,9-tetradeoxy-L-glycero-L-manno-non-2-ulosonic acid called pseudaminic acid, Pse5Ac7Ac and Pse5Ac7RHb where R indicates (R)-3-hydroxybutanoyl, have been found to occur in many capsular polysaccharide (CPS) types produced by isolates of an important human pathogen, Acinetobacter baumannii. The presence of either a psaABCEDF or psaABCGHF gene module at the K locus (KL) for CPS biosynthesis determines the type of the variant produced. Here, an A. baumannii clinical isolate 52-249, recovered in 2015 in Moscow, Russia, was found to include a novel psaABCIJF gene module in the KL218 sequence at the K locus. The CPS from 52-249 was extracted and studied by sugar analysis and partial acid hydrolysis along with one- and two-dimensional 1H and 13C NMR spectroscopy. A branched tetrasaccharide repeating unit was identified, which included a →3)-α-D-Galp-(1→6)-α-D-GlcpNAc-(1→3)-β-D-GalpNAc-(1→ main chain and Pse5Ac7Ac attached as a side branch, indicating that the psaABCIJF gene module is associated with synthesis of this variant. The K218 CPS was found to be structurally related to the K46 CPS of A. baumannii, and a comparison of the two structures enabled the assignment of glycosyltransferases. A KpsS3 protein for the α-(2→6) linkage of the Pse5Ac7Ac residue to D-Galp in K218 was identified.</p

The K139 capsular polysaccharide produced by Acinetobacter baumannii MAR17-1041 belongs to a group of related structures including K14, K37 and K116

Capsular polysaccharide (CPS) is a key target for bacteriophage and vaccine therapies currently being developed for treatment of infections caused by the extensively antibiotic resistant bacterial species, Acinetobacter baumannii. Identification of new CPS structures and the genetics that drive their synthesis underpins tailored treatment strategies. A novel CPS biosynthesis gene cluster, designated KL139, was identified in the whole genome sequence of a multiply antibiotic resistant clinical isolate, A. baumannii MAR-17-1041, recovered in Russia in 2017. CPS material extracted from A. baumannii MAR-17-1041 was studied by sugar analysis and Smith degradation along with one- and two-dimensional 1H and 13C NMR spectroscopy, and the structure was found to include a branched pentasaccharide repeating unit containing neutral carbohydrates. This structure closely resembles the topology of the A. baumannii K14 CPS but differs in the presence of D-Glcp in place of a D-Galp sugar in the repeat-unit main chain. The difference was attributed to a change in the sequence for two glycosyltransferases. These two proteins are also encoded by the A. baumannii KL37 gene cluster, and a multiple sequence alignment of KL139 with KL14 and KL37 revealed a hybrid relationship. The global distribution of KL139 was also assessed by probing 9065 A. baumannii genomes available in the NCBI non-redundant and WGS databases for the KL139 gene cluster. KL139 was found in 16 genomes from four different countries. Eleven of these isolates belong to the multidrug resistant global lineage, ST25.</p

Involvement of a Phage-Encoded Wzy Protein in the Polymerization of K127 Units To Form the Capsular Polysaccharide of Acinetobacter baumannii Isolate 36-1454

A comprehensive understanding of capsular polysaccharide (CPS) diversity is critical to implementation of phage therapy to treat panresistant Acinetobacter baumannii infections. Predictions from genome sequences can assist identification of the CPS type but can be complicated if genes outside the K locus (CPS biosynthesis gene cluster) are involved. Here, the CPS produced by A. baumannii clinical isolate 36-1454 carrying a novel K locus, KL127, was determined and compared to other CPSs. KL127 differs from KL128 in only two of the glycosyltransferase (gtr) genes. The K127 unit in 36-1454 CPS was the pentasaccharide b-D-Glcp-(1!6)-D-b-GalpNAc-(1!6)-a-D-Galp-(1!6)b-D-Glcp-(1!3)-b-D-GalpNAc in which D-Glcp at position 4 replaces D-Galp in K128, and the glycosyltransferases encoded by the different gtr genes form the surrounding linkages. However, although the KL127 and KL128 gene clusters encode nearly identical Wzy polymerases, the linkages between K units that form the CPS chains are different, i.e., b-D-GalpNAc-(1!3)-D-Galp in 36-1454 (K127) and b-D-GalpNAc-(1!4)-D-Galp in KZ-1093 (K128). The linkage between K127 units in 36-1454 is the same as the K-unit linkage in five known CPS structures, and a gene encoding a Wzy protein related to the Wzy of the corresponding K loci was found encoded in a prophage genome in the 36-1454 chromosome. Closely related Wzy proteins were encoded in unrelated phage in available KL127-carrying genomes. However, a clinical isolate, KZ-1257, carrying KL127 but not the prophage was found, and K127 units in the KZ-1257 CPS were b-DGalpNAc-(1!4)-D-Galp linked, confirming that WzyKL127 forms this linkage and thus that the phage-encoded WzyPh1 forms the b-D-GalpNAc-(1!3)-D-Galp linkage in 36-1454. IMPORTANCE Bacteriophage therapy is an attractive innovative treatment for infections caused by extensively drug resistant Acinetobacter baumannii, for which there are few effective antibiotic treatments remaining. Capsular polysaccharide (CPS) is a primary receptor for many lytic bacteriophages, and thus knowledge of the chemical structures of CPS produced by the species will underpin the identification of suitable phages for therapeutic cocktails. However, recent research has shown that some isolates carry additional genes outside of the CPS biosynthesis K locus, which can modify the CPS structure. These changes can subsequently alter phage receptor sites and may be a method utilized for natural phage resistance. Hence, it is critical to understand the genetics that drive CPS synthesis and the extent to which genes outside of the K locus can affect the CPS structure.</p

Acinetobacter baumannii K116 capsular polysaccharide structure is a hybrid of the K14 and revised K37 structures

The genome of Acinetobacter baumannii clinical isolate, MAR-303, recovered in Russia was sequenced and found to contain a novel gene cluster at the A. baumannii K locus for capsule biosynthesis. The gene cluster, designated KL116, included four genes for glycosyltransferases (Gtrs) and a gene for a Wzy polymerase responsible for joining oligosaccharide K units into the capsular polysaccharide (CPS). The arrangement of KL116 was a hybrid of previously described A. baumannii gene clusters, with two gtr genes and the wzy gene shared by KL37 and the two other gtr genes found in KL14. The structure of the K116 CPS was established by sugar analysis and Smith degradation, along with one- and two-dimensional 1H and 13C NMR spectroscopy. The CPS is composed of branched pentasaccharide K units containing only neutral sugars, with three monosaccharides in the main chain and a disaccharide side chain. The K116 unit shares internal sugar linkages with the K14 and K37 units, corresponding to the presence of shared gtr genes in the gene clusters. However, the specific linkage formed by Wzy was discrepant between K116 and the previously reported K37 CPS produced by A. baumannii isolate NIPH146. The K37 structure was therefore revised in this study, and the corrected Wzy linkage found to be identical to the Wzy linkage in K116. The KL116, KL14 and KL37 gene clusters were found in genomes of a variety of A. baumannii strain backgrounds, indicating their global distribution.</p