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Structural Evidence that the P/Q Domain of ZipA Is an Unstructured, Flexible Tether between the Membrane and the C-Terminal FtsZ-Binding Domain. Tomoo Ohashi, 2002.The cell division protein ZipA has an N-terminal transmembrane domain and a C-terminal globular domain that binds FtsZ . Between them are a charged domain and a P/Q domain rich in proline and glutamine that has been proposed to be an unfolded polypeptide . Here we provide evidence obtained by electron microscopy that the P/Q domain is a flexible tether ranging in length from 8 to 20 nm and invisible in rotary shadowing electron microscopy . We estimated a persistence length of 0.66 nm, which is similar to the persistence lengths of other unfolded and unstructured polypeptides . Competition between MutY and Mismatch Repair at A · C Mispairs In Vivo. Mandy Kim, 2003.We show that the MutY protein competes with the MutS-dependent mismatch repair system to process at least some A · C mispairs in vivo, converting them to G · C pairs . In the presence of an increased dCTP pool resulting from the loss of nucleotide diphosphate kinase, the frequency of A · T  G · C transitions at a hot spot in the rpoB gene is 30-fold lower in a MutY-deficient derivative than in the wild type .
Characterization, Expression, and Mutation of the Lactococcus lactis galPMKTE Genes, Involved in Galactose Utilization via the Leloir Pathway. Benoît P. Grossiord, 2003.A cluster containing five similarly oriented genes involved in the metabolism of galactose via the Leloir pathway in Lactococcus lactis subsp . cremoris MG1363 was cloned and characterized . The order of the genes is galPMKTE, and these genes encode a galactose permease (GalP), an aldose 1-epimerase (GalM), a galactokinase (GalK), a hexose-1-phosphate uridylyltransferase (GalT), and a UDP-glucose 4-epimerase (GalE), respectively . This genetic organization reflects the order of the metabolic conversions during galactose utilization via the Leloir pathway . The functionality of the galP, galK, galT, and galE genes was shown by complementation studies performed with both Escherichia coli and L . lactis mutants . The GalP permease is a new member of the galactoside-pentose-hexuronide family of transporters . The capacity of GalP to transport galactose was demonstrated by using galP disruption mutant strains of L . lactis MG1363 . A galK deletion was constructed by replacement recombination, and the mutant strain was not able to ferment galactose . Disruption of the galE gene resulted in a deficiency in cell separation along with the appearance of a long-chain phenotype when cells were grown on glucose as the sole carbon source . Recovery of the wild-type phenotype for the galE mutant was obtained either by genetic complementation or by addition of galactose to the growth medium .
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