The FN3 and BRCT motifs in the exomer component Chs5p define a conserved module that is necessary and sufficient for its function.
Chs5p is a component of the exomer, a coat complex required to transport the chitin synthase Chs3p from the trans-Golgi network to the plasma membrane. The Chs5p N-terminal region exhibits fibronectin type III (FN3) and BRCT domains. FN3 domains are present in proteins that mediate adhesion processes, whereas BRCT domains are involved in DNA repair. Several fungi--including Schizosaccharomyces pombe, which has no detectable amounts of chitin--have proteins similar to Chs5p. Here we show that the FN3 and BRCT motifs in Chs5p behave as a module that is necessary and sufficient for Chs5p localization and for cargo delivery. The N-terminal regions of S. cerevisiae Chs5p and S. pombe Cfr1p are interchangeable in terms of Golgi localization, but not in terms of exomer assembly, showing that the conserved function of this module is protein retention in this organelle and that the interaction between the exomer components is organism-specific.
Departamento de Microbiología y Genética/Instituto de Microbiología Bioquímica, Universidad de Salamanca/CSIC, Edificio Departamental, Campus Miguel de Unamuno, 37007, Salamanca, Spain.
Rebeca
R
Martín-García
Nagore
N
de León
Mohammad Reza
MR
Sharifmoghadam
M-Ángeles
MÁ
Curto
Marta
M
Hoya
Pilar
P
Bustos-Sanmamed
M-Henar
MH
Valdivieso
D000595:Amino Acid Sequence; D020126:Brefeldin A / Q000494:pharmacology; D002686:Chitin / Q000378:metabolism; D002687:Chitin Synthase / Q000032:analysis / Q000737:chemistry* / Q000378:metabolism*; D008969:Molecular Sequence Data; D054730:Protein Interaction Domains and Motifs; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000032:analysis / Q000737:chemistry* / Q000378:metabolism*; D012568:Schizosaccharomyces / Q000378:metabolism; D029702:Schizosaccharomyces pombe Proteins / Q000032:analysis / Q000378:metabolism; D021601:trans-Golgi Network / Q000378:metabolism
D029701:Saccharomyces cerevisiae Proteins; D029702:Schizosaccharomyces pombe Proteins; D002686:Chitin; D020126:Brefeldin A; C069390:CHS3 protein, S cerevisiae; C491360:CHS5 protein, S cerevisiae; D002687:Chitin Synthase