Regulation of gluconate and ketogluconate production in Gluconobacter oxydans ATCC 621-H

Gluconobacter spp. possess the enzymic potential for two pathways of direct glucose oxidation. It has been proposed that the major part of glucose is oxidized to gluconate via NADP-dependent glucose dehydrogenase and that reoxidation of NADPH under these conditions proceeds via recycling of gluconate through ketogluconates. This hypothesis was tested in experiments in which Gluconobacter oxydans ATCC 621-H was grown in glucose-yeast extract medium containing [¹⁴C]2-ketogluconate. As expected, glucose was almost quantitatively oxidized to gluconate, without further accumulation of 2- and 5-ketogluconate. Interestingly, the total amount of neither [¹⁴C]2-ketogluconate nor [¹⁴C]gluconate did change significantly during this oxidation phase, indicating that recycling of gluconate through ketogluconates did not occur. An analysis of enzyme activities in cell-free extracts of glucose-grown cells of G. oxydans ATCC 621-H showed that the membrane-bound glucose dehydrogenase was far more active than the NADP-linked glucose dehydrogenase. The activity of the latter enzyme constituted only 10–15% of that of quinoprotein glucose dehydrogenase and was far too low to match the in vivo rates of gluconate production in batch cultures of G. oxydans. It is concluded that under these conditions glucose is mainly oxidized to gluconate via the membrane-bound glucose dehydrogenase. Implications of these results for the regulation of ketogluconate formation are discussed.Abbreviations DCPIP 2,6-dichlorophenolindophenol - PMS phenazine methosulphate - PQQ pyrrolo-quinoline quinone     

Fine mapping of the 1q21 breakpoint of the papillary renal cell carcinoma-associated (X;1) translocation

A combination of Southern blot analysis on a panel of tumor-derived somatic cell hybrids and fluorescence in situ hybridization (FISH) techniques was used to map a series of DNA markers relative to the 1q21 breakpoint of the renal cell carcinoma (RCC)-associated (X;1)(p11;q21) translocation. This breakpoint maps between several members of the S100 family which are clustered in the 1q21 region and a conserved region between man and mouse containing the markers SPTA1-CRP-APCS-FcER1A-ATP1A2-APOA2. The location of the breakpoint coincides with the transition of a region of synteny of human chromosome 1 with mouse chromosomes 3 and 1. Received: 10 November 1995 / Revised: 3 February 1996