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*

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

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

Amino Acid Substitution ; Drug Resistance, Multiple, Bacterial ; physiology ; Escherichia coli ; physiology ; Escherichia coli Proteins ; genetics ; metabolism ; Membrane Potentials ; physiology ; Models, Biological ; Multidrug Resistance-Associated Proteins ; genetics ; metabolism ; Mutation, Missense

Amino Acid Substitution ; Arsenicals ; pharmacology ; Cell Line ; Chlorides ; pharmacology ; Drug Resistance, Neoplasm ; genetics ; Humans ; Mutation, Missense ; Oncogene Proteins, Fusion ; genetics ; metabolism

OBJECTIVETo report on a novel HLA-A allele, A*29:49, identified in a Chinese Han population by sequence based typing (SBT).

METHODSA donor from China Marrow Donor Programme (CMDP) was typed with a bi-allelic PCR-SBT kit, and no full matched result was obtained for the HLA-A locus. The novel HLA allele was verified with an allele-specific amplification SBT kit.

RESULTSA novel HLA-A allele was identified, which has differed by one nucleotide from the closest matched allele, HLA-A*29:01:01:01, at position 368(A→T), codon 99 (TAT→TTT), resulting in an amino acid substitution (Y→F). Another allele was verified as A*02:06:01.

CONCLUSIONA novel HLA-A allele was identified and officially named as HLA-A*29:49 by the WHO Nomenclature Committee for Factors of the HLA System.

Alleles ; Amino Acid Substitution ; genetics ; Base Sequence ; China ; HLA-A Antigens ; genetics ; Humans ; Sequence Analysis, DNA ; methods

β/γ-Crystallins are predominant structural proteins in the cytoplasm of lens fiber cells and share a similar fold composing of four Greek-key motifs divided into two domains. Numerous cataract-causing mutations have been identified in various β/γ-crystallins, but the mechanisms underlying cataract caused by most mutations remains uncharacterized. The S228P mutation in βB1-crystallin has been linked to autosomal dominant congenital nuclear cataract. Here we found that the S228P mutant was prone to aggregate and degrade in both of the human and E. coli cells. The intracellular S228P aggregates could be redissolved by lanosterol. The S228P mutation modified the refolding pathway of βB1-crystallin by affecting the formation of the dimeric intermediate but not the monomeric intermediate. Compared with native βB1-crystallin, the refolded S228P protein had less packed structures, unquenched Trp fluorophores and increased hydrophobic exposure. The refolded S228P protein was prone to aggregate at the physiological temperature and decreased the protective effect of βB1-crystallin on βA3-crystallin. Molecular dynamic simulation studies indicated that the mutation decreased the subunit binding energy and modified the distribution of surface electrostatic potentials. More importantly, the mutation separated two interacting loops in the C-terminal domain, which shielded the hydrophobic core from solvent in native βB1-crystallin. These two interacting loops are highly conserved in both of the N- and C-terminal domains of all β/γ-crystallins. We propose that these two interacting loops play an important role in the folding and structural stability of β/γ-crystallin domains by protecting the hydrophobic core from solvent access.
Amino Acid Substitution ; Cataract ; genetics ; metabolism ; HeLa Cells ; Humans ; Molecular Dynamics Simulation ; Mutation, Missense ; Protein Aggregation, Pathological ; genetics ; metabolism ; Protein Domains ; Protein Structure, Secondary ; Proteolysis ; beta-Crystallin B Chain ; chemistry ; genetics ; metabolism