Myosin Motor-Like Domain of the Class VI Chitin Synthase CsmB Is Essential to Its Functions inAspergillus nidulans

Myosin Motor-Like Domain of Class VI Chitin Synthase CsmB of <i>Aspergillus nidulans</i> Is Not Functionally Equivalent to That of Class V Chitin Synthase CsmA

“…We have found that CsmB lacking its MMD was susceptible to degradation. 17) We have also observed that MACB was more stable than CB itself (unpublished results). These facts imply that the functional difference between MA and MB might arise from the better stabilizing effect of MA on CSDs than that of MB, although the intracellular levels of chimeric proteins did not appear much different.…”

“…Since the calculated molecular masses of MBCA-HA and MACB-FLAG were 204 kDa and 210 kDa, respectively, the signals of 210 kDa and 220 kDa in the cell extracts of MBCA-HAÁA1 and MACB-FLAGÁB1 respectively are likely to have been post-translationally modified products, as in the cases of CsmA-HA and CsmB-FLAG. 17) These results indicate that most of the MBCA-HA and MACB-FLAG in the cells were present as full-length proteins. The fluorescence of MBCA-HA and MACB-FLAG was observed near actin structures at the hyphal tips and forming septa by indirect immunofluorescence microscopy using anti-HA or anti-FLAG and anti-actin antibodies.…”

“…16,17) In the present study, we examined the à The ratios of these data for the ÁcsmA/argB1, MACBÁA1, and MBCAÁA1 strains to those for the ÁcsmA/csmA1 strain are shown in parentheses. a Data are mean AE SD (n ¼ 3).…”

“…The MMDs of CsmA and CsmB bind to actin filaments in vitro and the interaction between MMD and actin is important for proper localization and normal functioning. 7,16,17) These findings suggest that CsmA and CsmB have overlapping functions that are essential for hyphal tip growth. The phenotypes of the csmA and csmB deletion mutants differ in some respects, and overexpression of csmA and of csmB does not suppress the defects of the csmB and csmA deletion mutants respectively.…”

“…The phenotypes of the csmA and csmB deletion mutants differ in some respects, and overexpression of csmA and of csmB does not suppress the defects of the csmB and csmA deletion mutants respectively. 7,17) Thus it is probable that CsmA and CsmB have specific functions. The amino acid sequence identity between the CSDs of CsmA and CsmB is 55%, while that between the MMDs is only 21%.…”