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PubMed | CAS Institute of Biophysics, Tianjin Xiqing Hospital, University of Florida, University of Chinese Academy of Sciences and 2 more.
Type: Journal Article | Journal: The Journal of biological chemistry | Year: 2016

The partially de-N-acetylated poly--1,6-N-acetyl-d-glucosamine (dPNAG) polymer serves as an intercellular biofilm adhesin that plays an essential role for the development and maintenance of integrity of biofilms of diverse bacterial species. Translocation of dPNAG across the bacterial outer membrane is mediated by a tetratricopeptide repeat-containing outer membrane protein, PgaA. To understand the molecular basis of dPNAG translocation, we determined the crystal structure of the C-terminal transmembrane domain of PgaA (residues 513-807). The structure reveals that PgaA forms a 16-strand transmembrane -barrel, closed by four loops on the extracellular surface. Half of the interior surface of the barrel that lies parallel to the translocation pathway is electronegative, suggesting that the corresponding negatively charged residues may assist the secretion of the positively charged dPNAG polymer. In vivo complementation assays in a pgaA deletion bacterial strain showed that a cluster of negatively charged residues proximal to the periplasm is necessary for biofilm formation. Biochemical analyses further revealed that the tetratricopeptide repeat domain of PgaA binds directly to the N-deacetylase PgaB and is critical for biofilm formation. Our studies support a model in which the positively charged PgaB-bound dPNAG polymer is delivered to PgaA through the PgaA-PgaB interaction and is further targeted to the -barrel lumen of PgaA potentially via a charge complementarity mechanism, thus priming the translocation of dPNAG across the bacterial outer membrane.

Fan X.,The Eighth Peoples Hospital Of Dongguan | Peng Q.,Dongguan Institute of Pediatrics | Chen Y.,BGI Shenzhen | Ma Z.,The Eighth Peoples Hospital Of Dongguan | And 7 more authors.
Genes and Genomics | Year: 2015

The aim of this study was to test the impact of variants rs900400 (located near LEKR1 and CCNL1) and rs9883204 (located in ADCY5) on birth weight in a Chinese population. We conducted a case–control study including 156 low-birth- weight infants as the case group and 100 normal-birth-weight infants as the control group. The rs900400 and rs9883204 variants were analyzed by gene sequencing in all the participants. Our results revealed a significant difference in the genotype distribution (χ2 = 10.449, p = 0.005) and allele distribution (χ2 = 9.277, p = 0.002) of rs900400 between the case group and the control group. The C allele of rs900400 was associated with lower birth weight (OR 1.771 [95 % CI 1.237–2.535]) in the Chinese population. However, the rs9883204 polymorphism was not informative in the Chinese population. Our study shows that the “birth weight-lowering” variant rs900400 located near LEKR1 and CCNL1, which is strongly associated with birth weight in European cohorts, appears to have a similar association in Chinese cohorts. However, the rs9883204 variant located in ADCY5 does not appear to be correlated with low birth weight in the same population. Moreover, we found that the variant rs900400 may also be associated with premature birth, thereby supporting the need for further research in this area. © 2015, The Genetics Society of Korea and Springer-Science and Media.

PubMed | The Eighth Peoples Hospital of Dongguan
Type: Journal Article | Journal: PloS one | Year: 2015

Glucose-6-phosphate dehydrogenase (G6PD) deficiency is a common enzymatic disorder of the erythrocytes that affects 400 million people worldwide. We developed a PCR-reverse dot blot (RDB) assay to screen twenty genotypes of seventeen Chinese G6PD mutations and investigate the spectrum of G6PD deficiency mutations in Dongguan District, Guangdong Province, in southern China.The PCR-RDB assay consists of multiplex PCR amplification of seven fragments in the G6PD target sequence of wild-type and mutant genomic DNA samples followed by hybridization to a test strip containing allele-specific oligonucleotide probes. A total of 16,464 individuals were analyzed by a combination of phenotypic screening and genotypic detection using the PCR-RDB assay and DNA sequence analysis.The PCR-RDB assay had a detection rate of 98.1%, which was validated by direct sequencing in a blind study with 100% concordance. The G6PD deficiency incidence rate in Dongguan District is 4.08%. Thirty-two genotypes from 469 individuals were found. The two most common variants were c.1376G>T and c.1388G>A, followed by c.95A>G, c.871G>A, c.392G>T, and c.1024 C>T. In addition, two rare mutations (c.703C>A and c.406C>T) were detected by DNA sequencing analysis. In our study, 65 cases harbored the C1311T/IVS polymorphism and 67 cases were homozygote.The PCR-RDB assay we established is a reliable and effective method for screening G6PD mutations in the Chinese population. Data on the spectrum of mutations in the Dongguan District is beneficial to the clinical diagnosis and prevention of G6PD deficiency.

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