Role of proline residues in the structure and function of a membrane transport protein

dc.contributor.authorConsler, T. G.en
dc.contributor.authorTsolas, O.en
dc.contributor.authorKaback, H. R.en
dc.date.accessioned2015-11-24T18:53:10Z
dc.date.available2015-11-24T18:53:10Z
dc.identifier.issn0006-2960-
dc.identifier.urihttps://olympias.lib.uoi.gr/jspui/handle/123456789/18511
dc.rightsDefault Licence-
dc.subjectAmino Acid Sequenceen
dc.subjectBase Sequenceen
dc.subjectBiological Transport, Activeen
dc.subjectBlotting, Westernen
dc.subjectDNA Mutational Analysisen
dc.subjectEscherichia colien
dc.subject*Escherichia coli Proteinsen
dc.subjectLactose/metabolismen
dc.subjectMembrane Proteins/physiologyen
dc.subjectMembrane Transport Proteins/genetics/*metabolismen
dc.subjectMolecular Sequence Dataen
dc.subject*Monosaccharide Transport Proteinsen
dc.subjectProline/*physiologyen
dc.subjectStructure-Activity Relationshipen
dc.subject*Symportersen
dc.titleRole of proline residues in the structure and function of a membrane transport proteinen
heal.abstractBy use of site-directed mutagenesis, each prolyl residue in the lac permease of Escherichia coli at positions 28 (putative helix I), 31 (helix I), 61 (helix II), 89 (helix III), 97 (helix III), 123 (helix IV), 192 (putative hydrophilic region 7), 220 (helix VII), 280 (helix VIII), and 327 [helix X; Lolkema, J. S., et al. (1988) Biochemistry 27, 8307] was systematically replaced with Gly, Ala, or Leu or deleted by truncation of the C-terminus [i.e., Pro403 and Pro405; Roepe, P.D., et al. (1989) Proc. Natl. Acad. Sci. U.S.A. 86, 3992]. Replacements were chosen on the basis of side-chain helical propensity: Gly, like Pro, is thought to be a "helix breaker", while Ala and Leu are "helix makers". With the exception of Pro28, each prolyl residue can be replaced with Gly or Ala, and Pro403 and -405 can be deleted with the C-terminal tail, and significant lac permease activity is retained. In contrast, when Pro28 is replaced with Gly, Ala, or Ser, lactose transport is abolished, but permease with Ser28 binds p-nitrophenyl alpha-D-galactopyranoside and catalyzes active transport of beta-galactopyranosyl-1-thio-beta-D- galactopyranoside. Replacement of Pro28, -31, -123, -280, or -327 with Leu abolishes lactose transport, while replacement of Pro61, -89, -97, or -220 with Leu has relatively minor effects. None of the alterations in permease activity is due to inability of the mutant proteins to insert into the membrane or to diminished lifetimes after insertion, since the concentration of each mutant permease in the membrane is comparable to that of wild-type permease as judged by immunological analyses.(ABSTRACT TRUNCATED AT 250 WORDS)en
heal.accesscampus-
heal.fullTextAvailabilityTRUE-
heal.identifier.secondaryhttp://www.ncbi.nlm.nih.gov/pubmed/1991110-
heal.identifier.secondaryhttp://pubs.acs.org/doi/pdf/10.1021/bi00219a019-
heal.journalNameBiochemistryen
heal.journalTypepeer-reviewed-
heal.languageen-
heal.publicationDate1991-
heal.recordProviderΠανεπιστήμιο Ιωαννίνων. Σχολή Επιστημών Υγείας. Τμήμα Ιατρικήςel
heal.typejournalArticle-
heal.type.elΆρθρο Περιοδικούel
heal.type.enJournal articleen

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