Collagen, a vital matrix protein for various tissue and functions in animals, is widely applied in biomaterials. In type Ⅰ collagen, missense mutations of glycine (Gly) in the Gly-Xaa-Yaa triplet of the triple helix are a major cause of osteogenesis imperfecta (OI). Clinical manifestations exhibit marked heterogeneity, spanning a broad disease spectrum from mild skeletal fragility (Type Ⅰ) to severe limb deformities (Type Ⅲ) and perinatal lethal forms (Type Ⅱ). This study utilized recombinant collagen as a model to further elucidate whether Gly→Ala/Val mutations at the N-terminus of the integrin-binding sequence GFPGER affect collagen structure and function, and to explore the underlying mechanisms by which missense mutations impact the biological function of collagen. By introducing Ala and Val substitutions at seven Gly positions N-terminal to the GFPGER sequence, we systematically assessed the effects of these amino acid replacements on the triple-helical structure, thermal stability, integrin-binding ability, and cell adhesion of recombinant collagen. All constructs formed a stable triple-helix structure, with slightly compromised thermal stability. Gly→Val substitutions increased the susceptibility of recombinant collagen to trypsin, which suggested local conformational perturbations in the triple helix. In addition, Gly→Val substitutions significantly reduced the integrin-binding affinity and decreased HT1080 cell adhesion, with the effects stronger than Gly→Ala substitutions. Compared with Gly→Ala substitutions, substitution of Gly with the larger residue Val had enhanced negative effects on the structure and function of recombinant collagen. These findings provide new insights into the molecular mechanisms of osteogenesis imperfecta and offer theoretical references and experimental foundations for the design of collagen sequences and the development of collagen-based biomaterials.
Recombinant Proteins/biosynthesis* ; Glycine/genetics* ; Humans ; Osteogenesis Imperfecta/genetics* ; Integrins/metabolism* ; Collagen/metabolism* ; Collagen Type I/metabolism* ; Amino Acid Substitution ; Mutation ; Mutation, Missense

Amino Acid Substitution ; Antineoplastic Agents/pharmacology* ; Cell Line, Tumor ; Drug Resistance, Neoplasm/genetics* ; Gastrointestinal Neoplasms/pathology* ; Humans ; MAP Kinase Signaling System/genetics* ; Mutation, Missense ; Receptor, ErbB-3/metabolism* ; Receptor, Fibroblast Growth Factor, Type 1/metabolism*

BACKGROUND: Enterococcus faecalis strains with low-level resistance to linezolid (an oxazolidinone antibiotic) have become common. No large-scale study has examined the underlying mechanisms in linezolid-resistant E. faecalis (LRE) strains. We investigated these mechanisms and molecular characteristics in Chongqing, China. METHODS: A total of 1,120 non-duplicated E. faecalis strains collected from August 2014 to June 2017 underwent drug susceptibility testing. LRE strains were screened for optrA, cfr, and mutations in the 23S rRNA and ribosomal proteins L3 and L4 by PCR amplification and sequencing. Multi-locus sequence typing (MLST) and pulsed-field gel electrophoresis (PFGE) were used for epidemiological analysis. RESULTS: All 43 low-level LRE strains (minimum inhibitory concentration: 8–16 mg/L) harbored optrA; cfr and 23S rRNA mutations were not detected. Novel mutations in the ribosomal proteins L3 and L4—one deletion (Q103del) and four substitutions (S113L, T35A, I98V, and N79D)—were identified. Novel amino acid substitutions at positions E60K, G197D, and T285P of the OptrA protein were observed. MLST revealed 20 types of LRE strains; the most common type was ST16 (32.6%). PFGE showed 14 strains of ST16 with unique banding patterns. Eight novel sequence types (ST823 to ST830) and one allele (gki95) were identified for the first time in China. CONCLUSIONS: optrA plays an important role in linezolid resistance and may serve as a marker for resistance screening. Since the L3 and L4 mutations did not simultaneously occur in the same strain, they play a negligible role in linezolid resistance. Epidemiological investigation suggested that the LRE cases were sporadic.
Alleles ; Amino Acid Substitution ; China* ; Electrophoresis, Gel, Pulsed-Field ; Enterococcus faecalis* ; Enterococcus* ; Epidemiology ; Linezolid ; Mass Screening ; Molecular Epidemiology* ; Polymerase Chain Reaction ; Ribosomal Proteins

No abstract available.
Amino Acid Substitution ; Korea ; Penicillin-Binding Proteins ; Penicillins ; Streptococcus

OBJECTIVE: To explore the molecular basis for a blood donor with an ABO subtype. METHODS: The proband and his family members were subjected to serological analysis. Their genotypes were determined by real-time PCR and sequencing of the coding regions of ABO gene. RESULTS: The proband was determined as an ABw subtype. By sequencing analysis, the proband was typed as A102/BW03. Compared with ABO*B.01, the proband was found to harbor a 721C>T variant (ABO*BW.03 allele) in exon 7 of the ABO gene, which caused substitution of Arginine at position 241 by Tryptophan resulting in a ABW phenotype. The blood type of the proband's sister was similar to that of the proband. The maternal serological pattern was B type, and the result of sequencing suggested that the genotype fit with B101/Bw03. CONCLUSION The 721C>T in the exon 7 of the ABO glycosyltransferase gene probably underlies the Bw03 phenotype. The ABO*Bw.03 variant of the proband and his sister were inherited from their mother.
ABO Blood-Group System ; genetics ; Amino Acid Substitution ; Female ; Genotype ; Humans ; Male ; Pedigree ; Whole Exome Sequencing

Isolates of 24 enterococci, 5 Enterococcus casseliflavus and 19 Enterococcus gallinarum, possessing vanC genes and showing low-level resistance to vancomycin were obtained from mice from commercial mouse breeding companies. Since some of these isolates showed resistance to other antibiotics, the purpose of this study was to clarify the resistant profiles of these isolates. One E. casseliflavus isolate showed resistance to erythromycin with a minimal inhibitory concentration (MIC) of 8 μg/mL and also showed apparent resistance to fluoroquinolones with an MIC of 32 μg/mL for ciprofloxacin. The MICs of 2 other fluoroquinolone-resistant E. casseliflavus and E. gallinarum isolates were 3 and 6 μg/mL, respectively. These 3 resistant isolates showed an absence of macrolide- and fluoroquinolone-resistant genes, including amino acid substitutions in the quinolone resistance determining regions of DNA gyrase and topoisomerase IV. Resistance to tetracycline was detected in 2 E. gallinarum isolates that were highly resistant, exhibiting MICs of 48 and 64 μg/mL and possessing tet(O) genes. The results indicate that antibiotic-resistant enterococci are being maintained in some laboratory mouse strains that have never been treated with an antibiotic.
Amino Acid Substitution ; Animals ; Anti-Bacterial Agents ; Breeding ; Ciprofloxacin ; DNA Gyrase ; DNA Topoisomerase IV ; Drug Resistance, Microbial ; Enterococcus ; Erythromycin ; Fluoroquinolones ; Mice ; Tetracycline ; Vancomycin

OBJECTIVE: To explore the serological and molecular characteristics of a female with the B(A) phenotype and safety issues related to her blood transfusion. METHODS: The B(A) phenotype of the proband was confirmed by serological testing. Her genotype was determined by using polymerase chain reaction-sequence specific primer (PCR-SSP) and direct sequencing of exons 6 and 7 of the ABO locus. Clinical condition of her blood transfusion was also reviewed. RESULTS: Both A and B antigens were detected on the red blood cells derived from the proband, while anti-A antibody was detected in her serum. The result of PCR-SSP suggested that she has a B/O02 phenotype. DNA sequencing revealed presence of 297A>G, 526C>G, 657C>T, 700C>G, 703G>A, 796C>A, 803G>C and 930G>A mutations. The genotype of the proband was deduced as B(A) 02/O02. Compared with the B101 allele, the B(A)02 allele has a nucleotide change (C>G) at position 700, which resulted in substitution of an amino acid (P234A). The result of cross match testing between the proband and two donors with an AB phenotype was consistent. No adverse reaction was observed after the transfusion. CONCLUSION 700G>C of B allele can result in the B(A) phenotype, which is similar to AB. Blood donors for individuals with the B(A) phenotype should include those with an AB phenotype.
ABO Blood-Group System ; genetics ; Alleles ; Amino Acid Substitution ; Blood Grouping and Crossmatching ; Blood Transfusion ; Exons ; Female ; Genotype ; Humans ; Phenotype ; Polymorphism, Single Nucleotide

OBJECTIVE: To explore the molecular basis for an individual with Ax28 phenotype of the ABO subtype. METHODS: The ABO group antigens on red blood cells of the proband were identified by monoclonal antibodies. The ABO antibody in serum was detected by standard A, B, O cells. Exons 1 to 7 of the ABO gene were respectively amplified by PCR and directly sequenced. Amplicons for exons 5 to 7 were also sequenced after cloning. RESULTS: Weakened A antigen was detected on red blood cells from the proband. Both anti-A and anti-B antibodies were detected in the serum. Heterozygous 261G/del was detected in exon 6, while heterozygous 467C/T and 830T/C were detected in exon 7 by direct DNA sequencing. After cloning and sequencing, two alleles (O01 and Ax28) were obtained. Compared with A102, the sequence of Ax28 contained one nucleotide changes (T to C) at position 830, which resulted in amino acid change (Val to Ala) at position 277. CONCLUSION The novel mutation c.830T>C of the galactosaminyltransferase gene may give rise to the Ax28 phenotype.
ABO Blood-Group System ; genetics ; Alleles ; Amino Acid Substitution ; Exons ; Galactosyltransferases ; genetics ; Genotype ; Humans ; Phenotype ; Polymorphism, Single Nucleotide ; Sequence Deletion

OBJECTIVETo analyze a sample with ABO subgroup using serological and molecular methods.

METHODSThe ABO phenotype of the sample was determined with a tube method, and the activity of glycosyltransferases was determined with an uridine diphosphate galactose transferring method. The ABO gene of the propositus was identified by PCR with sequence-specific primers (PCR-SSP). In addition, exons 6 and 7 of the ABO gene were cloned and sequenced.

RESULTSNeither A nor B antigen was identified in the propositus, despite that its anti-B antibody was found to be attenuated. No activity of α -1, 3-D-galactosyltransferase was detected in the serum. The presence of B and O alleles were confirmed by PCR-SSP, and a novel mutation (562C to T) of the exon 7 was confirmed by sequencing, which has led to an amino acid substitution (Arg to Cys) at position 188. The genotype of the propositus was determined as Bnew/O.

CONCLUSIONA novel B allele has been identified, which was named as Bw39 by the Blood Group Antigen Gene Mutation Database (BGMUT).

ABO Blood-Group System ; genetics ; Adult ; Alleles ; Amino Acid Substitution ; Base Sequence ; Exons ; Galactosyltransferases ; genetics ; Humans ; Male ; Molecular Sequence Data ; Point Mutation

Rabies virus (RABV) causes a neurological disease in warm-blooded animals that is nearly always fatal. In this study, we analyzed the matrix (M) genes in 10 Korean street RABV strains isolated from two Provinces during 2011–2013. The M genes in these 10 Korean strains were highly conserved during 1999–2013. Phylogenetic analysis revealed they were closely related to the M genes of RABVs isolated in northeastern China. Specific amino acid substitutions were identified in the KRVB1206, KRVF1301, and BV9901PJ strains. However, functional domains, including those involved in virus production and pathogenicity, were conserved in all 10 strains.
Amino Acid Substitution ; Animals ; China ; Korea* ; Phylogeny ; Rabies virus* ; Rabies* ; Viral Matrix Proteins ; Virulence