The mature part of the chloroplast triose phosphate-phosphate translocator was cloned into the yeast expression vector pEVP11. This construct was used to transform cells from both Saccharomyces cerevisiae and the rmsion yeast Schizosaccharomyces pombe. The chloroplast translocator protein was functionally expressed in the transformed yeast cells and represented about 1-2% of the Sch. pombe cell membrane protein. It was localized to mitochondrial membranes and/or membranes of the rough endoplasmic reticulum. In order to purify the recombinant translocator protein, a sequence encoding a C-terminal tag of six histidine residues was introduced into the corresponding cDNA. The expressed histidine-tagged translocator protein was purified from the transformed yeast cells under nondenaturing conditions to apparent homogeneity by a single-step affinity chromatography using a Ni2+ nitrilotriacetic acid resin. Both the expressed triose phosphate translocator and the recombinant histidinetagged protein possess substrate specificities identical to those of the authentic chloroplast protein, providing definitive evidOnce for its identity as the triose phosphate translocator and further disproving its assignment as the receptor for chloroplast protein import. The yeast expression system in combination with the Ni2+ nitrilotriacetic acid chromatography thus provides a valuable tool for the production of purified membrane proteins in a functional state.During photosynthetic CO2 fixation, the fixed carbon (in the form of triose phosphates and 3-phosphoglycerate) is exported from the chloroplasts into the cytosol, where it is converted into other substances such as sucrose and amino acids. This transport is mediated by the Frankfurt) and the yeast expression vector pEVP11 was kindly provided by N. Sauer (University of Regensburg). All other chemicals were of the highest purity available.Cloning Procedures. The DNA encoding only the mature part of the spinach translocator protein was generated by PCR from the full-length cDNA clone encoding the entire precursor protein (2). As a sense primer, a synthetic oligonucleotide corresponding to the beginning of the mature part of the cTPT with an additional ATG codon was used (P1), and the second oligonucleotide was a (reverse) T7 primer. The resulting DNA fragment was first cloned into EcoRV-cut pBSC to yield clone pBSC-mPtra. This vector was digested with Sal I, the Sal I ends were filled in, and the Sal I-filled/BamHI fragment was then ligated into the Sac I-filled/BamHI-cut yeast expression vector pEVPll containing the S. cerevisiae LEU2+ gene (8) 2155The publication costs of this article were defrayed in part by page charge payment. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. §1734 solely to indicate this fact.

In a small group of patients, very high cytokine concentrations are a possible explanation for the cause of death ("cytokine storm").

With the aim of elucidating the mechanisms involved in the biosynthesis of medium-chain fatty acids in Cuphea lanceolata Ait., a crop accumulating up to 90% decanoic acid in seed triacylglycerols, cDNA clones of a beta-ketoacyl-acyl carrier protein (ACP) synthase IV (clKAS IV, EC 2.3.1.41) were isolated from C. lanceolata seed embryos. The amino acid sequence deduced from clKAS IV cDNA showed 80% identity to other plant KAS II-type enzymes, 55% identity towards plant KAS I and over 90% towards other Cuphea KAS IV-type sequences. Recombinant clKAS IV was functionally overexpressed in Escherichia coli, and substrate specificity of purified enzyme showed strong preference for elongation of short-chain and medium-chain acyl-ACPs (C4- to C10-ACP) with nearly equal activity. Further elongation steps were catalysed with distinctly less activity. Moreover, short- and medium-chain acyl-ACPs exerted a chain-length-specific and concentration-dependent substrate inhibition of clKAS IV. Based on these findings a regulatory mechanism for medium-chain fatty acid synthesis in C. lanceolata is presented.

Helicobacter pylori infection is known to be one of the most common chronic infectious diseases in humans. Recently, a hypothesis was proposed that H. pylori infection could be a frequent cause for sudden infant death syndrome (SIDS). We have investigated this postulated association by examining formalin-fixed paraffin-embedded gastric tissues of a retrospective cohort of 94 SIDS cases: The presence of H. pylori was inferred from a newly developed real-time quantitative PCR assay with SYBR Green I detection. This assay is based on the amplification of the single-copy H. pylori-specific glmM gene. Accuracy and precision were verified using a plasmid containing a 977-bp fragment of this glmM gene. The assay was very sensitive, and as few as 30 template copies per PCR reaction could be detected even in the presence of excess human DNA. The assay was validated on mucosal biopsy samples of patients with known H. pylori infections. Interfering effects due to SIDS gastric tissue were excluded. Only two (2.1%) of the SIDS samples yielded H. pylori DNA copy numbers and only beyond the lowest standard concentration. These results could be confirmed independently by immunohistochemistry using an H. pylori-specific antibody. Thus, an infection by H. pylori is very rare in cases of SIDS, and thus the postulated association of H. pylori infection and SIDS cannot be confirmed.

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