Schultz et al. (1998) Proc. Natl. Acad. Sci. USA 95, 5857-5864
Letunic et al. (2012) Nucleic Acids Res , doi:10.1093/nar/gkr931

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SMI1_KNR4 SMI1 / KNR4 family

SMART accession number:	SM00860
Description:	Proteins in this family are involved in the regulation of 1,3-beta-glucan synthase activity and cell-wall formation.
Interpro abstract (IPR018958):	Proteins in this family are involved in the regulation of 1,3-beta-glucan synthase activity and cell-wall formation [(PUBMED:7937796), (PUBMED:8289782)]. Yeast members of this family are involved in the regulation of cell wall assembly. Saccharomyces cerevisiae (Baker's yeast) protein KNR4 (SMI1) has a regulatory role in chitin deposition and in cell wall assembly [(PUBMED:10206705)]. It was originally identified as a regulator of chitin synthase expression (acting as a repressor) [(PUBMED:10206705)] and of 1,3-beta-glucan synthase levels [(PUBMED:8289782)]. It was shown to localise in patches at presumptive bud sites in unbudded cells and at the incipient bud site during bud emergence [(PUBMED:10206705)]. KNR4 is believed to connect the PKC1-SLT2 MAPK pathway with cell proliferation. It has been shown to interact with BCK2, a gene involved in cell cycle progression in S. cerevisiae (forming a complex) to allow PKC1 to coordinate the cell cycle (cell proliferation) with cell wall integrity [(PUBMED:12185498), (PUBMED:12823808)]. PKC1 plays an essential role in cell wall integrity and cell proliferation through a bifurcated PKC1/mitogen-activated protein (MAP) kinase pathway. KNR4 also interacts with the tyrosine-tRNA synthetase protein encoded by TYS1 and is involved in sporulation process [(PUBMED:11410349)]. Note: previously reported evidence that KNR4 may interact with nuclear matrix-association region [(PUBMED:8516310)] may be due to an artefact [(PUBMED:10206705)].
Family alignment:	View or CHROMA formatCLUSTALW formatMSF formatFASTA formatPIR format

There are 1157 SMI1_KNR4 domains in 1141 proteins in SMART's nrdb database.

Click on the following links for more information.

• Evolution (species in which this domain is found)

• Click on to expand nodes. To display all proteins with a SMI1_KNR4 domain in a specific node, click on it.

  This tree shows only several representative species. The complete taxonomic breakdown of all proteins with SMI1_KNR4 domain is also avaliable.

  Useful shortcuts: Expand all nodes or Collapse tree
  Go to specific node: Anopheles gambiae, Drosophila melanogaster, Homo sapiens, Mus musculus, Rattus norvegicus, Saccharomyces cerevisiae, Takifugu rubripes

• Cellular role (predicted cellular role)

• Cellular role: replication
  

• Literature (relevant references for this domain)

• Primary literature is listed below; Automatically-derived, secondary literature is also avaliable.

  • Enderlin CS, Selitrennikoff CP
  • Cloning and characterization of a Neurospora crassa gene required for(1,3) beta-glucan synthase activity and cell wall formation.
  • Proc Natl Acad Sci U S A. 1994; 91: 9500-4
  • Display abstract

  • The glucan synthase 1 gene (gs-1) is required for (1,3) beta-glucansynthase activity [E.C. 2.4.1.34; UDP glucose:1,3-beta-D-glucan3-beta-D-glucosyltransferase] and for cell wall formation. The gs-1 genewas cloned by functional complementation of the cell-wall-less defect ofthe (1,3) beta-glucan synthase-deficient mutant, TM1, by using a genomicNeurospora crassa cosmid library. A 2568-nucleotide gs-1 cDNA sequencerevealed a 532-amino acid open reading frame encoding a polypeptide of 59kDa. The predicted gs-1 gene product has no obvious signal peptidecleavage sites or transmembrane domains. A gs-1 null mutant is defectivefor cell wall formation and (1,3) beta-glucan synthase activity. Thepredicted GS-1 protein is weakly homologous to a putative Saccharomycescerevisiae transcriptional regulatory protein.

  • Hong Z et al.
  • Cloning and characterization of KNR4, a yeast gene involved in(1,3)-beta-glucan synthesis.
  • Mol Cell Biol. 1994; 14: 1017-25
  • Display abstract

  • k9 killer toxin from Hansenula mrakii was used to select a number ofresistant mutants from Saccharomyces cerevisiae. Preliminary biochemicaland genetic studies showed that some of them acquired structural defectsin the cell wall. One of these mutants, the knr4-1 mutant, displays anumber of cell wall defects, including osmotic sensitivity; sensitivity tocercosporamide, a known antifungal agent; and resistance to Zymolyase, a(1,3)-beta-glucanase. We report here the isolation and analysis of theKNR4 gene. DNA sequence analysis revealed an uninterrupted open readingframe which contains five potential start codons. The longest codingtemplate encodes a protein of 505 amino acids with a calculated molecularmass of 57,044 Da. A data base search revealed 100% identity with anuclear protein, SMI1p. Disruption of the KNR4 locus does not result incell death; however, it leads to reduced levels of both (1,3)-beta-glucansynthase activity and (1,3)-beta-glucan content in the cell wall. The genewas mapped to the right arm of chromosome VII.

• Structure (3D structures containing this domain)

• 3D Structures of SMI1_KNR4 domains in PDB

  PDB code	Main view	Title
  2icg		Crystal structure of a protein of unknown function (np_472245.1) from listeria innocua at 1.65 a resolution
  2prv		Crystal structure of uncharacterized protein (np_389780.1) from bacillus subtilis at 1.30 a resolution
  3d5p		Crystal structure of putative glucan synthesis regulator of smi1/knr4 family (yp_211376.1) from bacteroides fragilis nctc 9343 at 1.45 a resolution

• Links (links to other resources describing this domain)

• PFAM	SMI1_KNR4
  INTERPRO	IPR018958

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