Functional Analysis Of CslA Gene In Strptomyces Coelicolor

Cellulose synthase and cellulose synthase-like proteins,responsible for synthesizingβ-glucan-containing polysaccharides,play a fundamental role in cellular architectures such as plant cell and tissue morphogenesis,bacterial biofilm formation and fruiting body development.However,the role of the proteins involved in the developmental process is not well understood.Here we report that a cellulose synthase-like protein(CslAsc) in Streptomyces has a function in hyphal tip growth and morphological differentiation.The cslAsc replacement mutant showed pleiotropic defects including the severe delay of aerial hyphae formation and altered cell wall morphology.Calcofluor white fluorescence analysis demonstrated that polysaccharide synthesis at hyphal tips was dependent on CslAsc.cslAsc was constitutively transcribed and a EGFP-CslAsc fusion protein was mostly located at the hyphal tips.An extract enriched in morphogenetic chaplin proteins promoted formation of aerial hyphae by the mutant.Furthermore,a two-hybrid experiment indicated that the glycosyltransferase domain of CslAsc interacted with the tropomyosin like polarity-determining DivIVA protein,suggesting that the tip-located DivIVA governed tip recruitment of the CslAsc membrane protein.These results imply that the cellulose synthase-like protein couples extracellular and cytoskeletal components functioning in tip growth and cell development.