Differential requirements of a mitotic acetyltransferase in somatic and germ line cells

Abstract

During mitosis different types of cells can have differential requirements for chromosome segregation. We isolated two new alleles of the separation anxiety gene (san). san was previously described in both Drosophila and in humans to be required for centromeric sister chromatid cohesion (Hou et al., 2007; Williams et al., 2003). Our work confirms and expands the observation that san is required in vivo for normal mitosis of different types of somatic cells. In addition, we suggest that san is also important for the correct resolution of chromosomes, implying a more general function of this acetyltransferase. Surprisingly, during oogenesis we cannot detect mitotic defects in germ line cells mutant for san. We hypothesize the female germ line stem cells have differential requirements for mitotic sister chromatid cohesion.

Drosophila aPKC is required for mitotic spindle orientation during symmetric division of epithelial cells

“…The apkc ts allele was isolated from a previously reported maternal screen (Pimenta-Marques et al, 2008). apkc ts zygotic mutant third instar larvae (L3) were obtained by crossing the apkc ts /CyO Actin-GFP stock with both the Df(2R)l4/CyO Actin-GFP and apkc k06403 /CyO Actin-GFP stocks.…”

“…Complementation group 5 contained a lethal allele and a maternal sterile allele (Pimenta-Marques et al, 2008). Both alleles were mapped using the Bloomington 2R deficiency kit.…”

“…Wing discs were mounted in Vectashield (Vector Laboratories). For maternal phenotypic analysis, 0-6 hour embryos were fixed and stained using standard procedures (Pimenta-Marques et al, 2008) except for F-actin staining, where the vitelline membrane was removed manually. The oogenesis phenotypic analysis was performed with tissue dissected from 2-or 3-dayold females, where mutant clones were induced by heat shock at first and second instar larval stages, and fixed in PBS containing 4% formaldehyde for 20 minutes.…”

“…Previously, we isolated a collection of maternal mutants defective for early embryonic development (Pimenta-Marques et al, 2008). From this collection we identified a new allele of atypical protein kinase C (apkc ts ) that contained a point mutation in a highly conserved phenylalanine within the protein kinase domain (from a phenylalanine to a leucine at position 532; F532L).…”

Structure of a Ternary Naa50p (NAT5/SAN) N-terminal Acetyltransferase Complex Reveals the Molecular Basis for Substrate-specific Acetylation

“…This protein complex contains two catalytic subunits, Naa10p (ARD1) and Naa50p, and two auxiliary subunits, Naa15p (NATH (N-acetyltransferase human)) and HYPK, which associate with the ribosome (9 -11). The human and fruit fly Naa50p enzymes are essential for normal sister chromatid cohesion and chromosome condensation, but the NatA complex was not implicated in this phenotype, suggesting that this is attributed solely by Naa50p-mediated NAT activity independent of the complex (12)(13)(14). However, the responsible substrate potentially requiring N-terminal acetylation for proper functioning remains to be identified.…”