title: The Serratia marcescens NucE protein functions as a holin in Escherichia coli.
abstract: The recently discovered nucC locus of Serratia marcescens encodes the cryptic prophage genes nucE, nucD, and nucC. NucC is required for expression of the S. marcescens nuclease and functions as a transcriptional activator of the nuclease gene, nucA. NucE and NucD are dispensable for nuclease expression but were proposed to allow for secretion of the nuclease by Escherichia coli. Here, we show (i) that the NucE protein is membrane bound, (ii) that it can complement the lambda S holin, (iii) that it can be triggered by potassium cyanide, (iv) that it is detrimental to cell viability, and (v) that the concomitant expression of nucE and nucD results in cell lysis. Apparently NucE and NucD function as a holin and an endolysin, respectively. This suggests that their roles in nuclease secretion by E. coli are indirect, possibly through directed cell lysis.
authors.affiliation: Institute of Microbiology and Genetics, Vienna Biocenter, University of Vienna, Austria.
authors.forename: M
authors.initials: M
authors.lastname: Berkmen
authors.forename: M J
authors.initials: MJ
authors.lastname: Benedik
authors.forename: U
authors.initials: U
authors.lastname: Bläsi
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D001433:Bacteriolysis; D002462:Cell Membrane / Q000378:metabolism; D010450:Endopeptidases / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D005816:Genetic Complementation Test; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D012706:Serratia marcescens / Q000235:genetics*; D014764:Viral Proteins / Q000737:chemistry / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D008565:Membrane Proteins; C108623:NucE protein, Serratia marcescens; C108624:S holin, bacteriophage lambda; D014764:Viral Proteins; D010450:Endopeptidases; C001143:endolysin