title: Two-step secretion of the Serratia marcescens extracellular nuclease.
abstract: The extracellular nuclease of Serratia marcescens is one of a wide variety of enzymes secreted into the growth medium. Its appearance occurs late in the growth of a culture, and its gene, nucA, is transcriptionally regulated in a complex fashion by growth phase and other factors. Pulse-labeling studies reveal that extracellular secretion of nuclease occurs as a two-step process. In the first step, nuclease is rapidly translocated across the cytoplasmic membrane into the periplasm, where it accumulates as a mature active nuclease. A precursor protein, nuclease still carrying its signal sequence, was detected in the presence of carbonyl cyanide m-chlorophenylhydrazone or sodium azide, suggesting that this initial translocation and signal processing step involves an energy-dependent and Sec-dependent pathway in S. marcescens. The second step of secretion across the outer membrane is a slow process requiring between 30 to 120 min, depending on growth conditions.
authors.affiliation: Department of Biochemical and Biophysical Sciences, University of Houston, Texas 77204-5934, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Suh
authors.forename: S
authors.initials: S
authors.lastname: Jin
authors.forename: T K
authors.initials: TK
authors.lastname: Ball
authors.forename: M J
authors.initials: MJ
authors.lastname: Benedik
mesh_terms: D001692:Biological Transport; D004706:Endodeoxyribonucleases / Q000378:metabolism*; D004722:Endoribonucleases / Q000378:metabolism*; D004792:Enzyme Precursors / Q000378:metabolism; D007700:Kinetics; D011499:Protein Processing, Post-Translational; D021382:Protein Sorting Signals / Q000378:metabolism; D012706:Serratia marcescens / Q000201:enzymology* / Q000254:growth & development
chemical_list: D004792:Enzyme Precursors; D021382:Protein Sorting Signals; D004706:Endodeoxyribonucleases; D004722:Endoribonucleases; C021835:Serratia marcescens nuclease