Haplotype association of calpain 10 gene variants with type 2 diabetes mellitus in an Irish sample.

BACKGROUND: Calpain 10 (CAPN10) gene may contribute to the pathogenesis of type 2 diabetes mellitus (T2DM). AIM: To examine the contribution of four CAPN10 gene variants to T2DM risk in an Irish sample. METHODS: Genotyping of marker 19 insertion-deletion (ins/del) and three CAPN10 variants, rs3792267, rs3749166 and rs5030952 at the CAPN10 gene was performed in 236 T2DM subjects and 120 controls. Allelic, genotypic and haplotype comparisons were conducted between the groups. RESULTS: In the examined markers, no significant differences were observed although the deletion/deletion allele tended to be more common in T2DM subjects (chi(2) = 3.2, P = 0.07). A significant overrepresentation of a haplotype comprising (rs3792267), (19) and rs3749166 (chi(2) = 5.3, P = 0.021) was seen in T2DM subjects. Two protective haplotypes were detected: (G-ins-G) of (rs3792267), (19) and rs3749166 (chi(2) = 6.7, P = 0.009) and (ins-G-C) of (19), (rs3749166) and rs5030952 (chi(2) = 8.5, P = 0.003). CONCLUSIONS: CAPN10 gene variants may affect T2DM susceptibility in the Irish population.

Prevalence of the metabolic syndrome in patients with diabetes mellitus.

BACKGROUND: Metabolic syndrome (MetS) is a vascular risk factor with prevalence in the general population of 17-25%. AIM: To determine the prevalence of MetS in patients with diabetes mellitus (DM). METHODS: A total of 200 patients [18% type 1 (T1DM), 82% type 2 (T2DM)] attending for annual review were studied. Standard blood tests were requested. Blood pressure and waist circumference were measured. Adult Treatment Panel III (ATP III) criteria for diagnosis of MetS were applied. RESULTS: A total of 122 (61%) patients had MetS. More patients with T2DM (69.5%) than TIDM (22.2%) had MetS. Despite treatment of DM (100%), hypertension (69.5%) and dyslipidaemia (48.3%), 114 patients (57%) still met the criteria for MetS at time of study. CONCLUSIONS: Most T2DM patients have MetS but it is uncommon in T1DM. Despite treatment, almost half of patients still met the criteria for MetS. Aggressive treatment of MetS components is required to reduce cardiovascular risk in DM.

The lytB gene of Escherichia coli is essential and specifies a product needed for isoprenoid biosynthesis.

LytB and GcpE, because they are codistributed with other pathway enzymes, have been predicted to catalyze unknown steps in the nonmevalonate pathway for isoprenoid biosynthesis. We constructed a conditional Escherichia coli lytB mutant and found that LytB is essential for survival and that depletion of LytB results in cell lysis, which is consistent with a role for this protein in isoprenoid biosynthesis. Alcohols which can be converted to pathway intermediates beyond the hypothesized LytB step(s) support limited growth of E. coli lytB mutants. An informatic analysis of protein structure suggested that GcpE is a globular protein of the TIM barrel class and that LytB is also a globular protein. Possible biochemical roles for LytB and GcpE are suggested.

Identification of sequence selective receptors for peptides with a carboxylic acid terminus.

Split-and-mix libraries of resin-bound "tweezer" receptors have been prepared and screened to identify receptors for dye-labelled tripeptides. The receptors incorporate a diamidopyridine unit to serve as a specific recognition site for the CO2H group, leading to strong and selective receptors for peptide guests with a CO2H terminus. The role of the dye-label, attached to the peptide guest to allow visualisation of selective recognition events in the screening experiments, has also been examined and was found to have a significant influence on the binding selectivities.

Autoregulation of the Escherichia coli replication initiator protein, DnaA, is indirect.

The expression of dnaA is autoregulated, in that transcription of the gene increases when DnaA is inactivated (and initiation of replication prevented) and decreases when DnaA is supplied in excess. However, the inactivation of DnaA does not necessarily lead to increased DnaA production, as dnaA(Ts; temperature sensitive) strains which are integratively suppressed by derivatives of the plasmid R1 do not show temperature-induced derepression. Several possible explanations for this unanticipated behaviour were considered and ruled out. We suggest here that the completion of a critical step in initiation may prevent dnaA derepression: although DnaA would be required to complete this step at oriC, DnaA(Ts) would be sufficient at the R1 origin. Autoregulation of dnaA has been attributed to the binding of DnaA at a consensus binding site in the dnaA promoter region. We show here, using reporter systems, that this DnaA-binding site is not required for the autoregulatory response. We find, further, that replacement of the chromosomal dnaA gene with one containing a mutated binding site causes no demonstrable phenotypic change: cells with the mutant gene show no disadvantage in competition with dnaA+ cells.

The coupling between ftsZ transcription and initiation of DNA replication is not mediated by the DnaA-boxes upstream of ftsZ or by DnaA.

The DnaA protein of Escherichia coli is a multi-functional protein which, In addition to promoting initiation of replication, can regulate the initiation or termination of transcription of a variety of genes. It acts by binding to DNA at a defined sequence, termed a DnaA-box. Three candidate DnaA-boxes which occur within the essential cell-division genes, ftsQ and ftsA, have been hypothesized to mediate the response of the downstream ftsZ gene to intracellular levels of DnaA, and thus to couple the processes of initiation and cell division. We show here that, although transcription from promoters upstream of ftsZ is increased when initiation of chromosome replication is blocked by DnaA inactivation, this response is not mediated by the DnaA-boxes near these promoters, nor is it specific to DnaA. We show, furthermore, that mutational inactivation of the putative DnaA-binding sites in the fts region of the chromosome does not lead to impaired growth or reduced survival of cells.

The tail of a chaperonin: the C-terminal region of Escherichia coli GroEL protein.

The active form of the HSP60 molecular chaperone of Escherichia coli, GroEL, is a pair of seven-membered rings. We have used site-directed mutagenesis to construct forms of the 547-amino-acid monomer truncated at the C-terminus. We show here that forms that are 520 amino acids long or longer are close to being fully functional. Removing one further amino acid, however, results in a protein, GroEL519, which retains little function. This truncated form is metabolically stable but is not recovered from the cell in particle form. When synthesized at high levels, it prevents the normal assembly of GroEL547 present in the same cell. When synthesized at low levels, it can be included, probably at low molar ratios, in particles formed by assembly-competent forms of GroEL. This can be seen as partial complementation of the temperature-sensitive mutant groEL44. We conclude that amino acid 520 is crucial for particle assembly. GroEL516 has in vivo properties similar to those of GroEL516 has in vivo properties similar to those of GroEL519, but the still shorter form, GroEL504, appears to be inactive.

Kinking of RNA helices by bulged bases, and the structure of the human immunodeficiency virus transactivator response element.

We have used gel electrophoresis to show that the pyrimidine bulge of the HIV-1 TAR sequence causes a local bending of the helical axis. The TAR bulge caused a retardation in electrophoretic mobility in polyacrylamide gels. When this was placed adjacent to an additional bulged sequence in a linear RNA fragment, the mobility of the molecule varied sinusoidally with the spacing between the two bulges. Electrophoretic mobilities suggested that the TAR sequence context of the pyrimidine bulge causes a greater degree of axial kinking than in an equivalent randomly chosen sequence. Experiments in which an A5 bulge was progressively opposed by adenine bases inserted in the opposite strand showed that even a single opposed adenine markedly reduced electrophoretic mobility, i.e. axial bending, and two adenine bases reduced the mobility virtually to that of a normal duplex. We suggest that the pronounced kinking resulting from an unopposed bulge provides a particularly recognizable feature in RNA, and that this is the basis of the interaction between the HIV Tat protein and the TAR sequence.