title: Linking genetics to structural biology: complex heterozygosity screening with actin alanine scan alleles identifies functionally related surfaces on yeast actin.
abstract: Previous genome-level genetic interaction screens with the single essential actin gene of yeast identified 238 nonessential genes that upon deletion result in deleterious, digenic complex haploinsufficiences with an actin null allele. Deletion alleles of these 238 genes were tested for complex heterozygous interactions with 32 actin alanine scan alleles, which target clusters of residues on the surface of actin. A total of 891 deleterious digenic combinations were identified with 203 of the 238 genes. Two-dimensional hierarchical cluster analysis of the interactions identified nine distinct groups, and the alleles within clusters tended to affect localized regions on the surface of actin. The mutants in one cluster all affect electrostatic interactions between stacked subunits in the long pitch helix of the actin filament. A second cluster that contains the most highly interactive alleles may disrupt the tropomyosin/myosin system, as one of the mutants in that cluster cannot support Type V myosin-dependent movement of secretory vesicles in haploids and causes processivity defects in heterozygous diploids. These examples suggest the clusters represent mutations with shared protein-protein interaction defects. These results show that complex heterozygous interaction screens have benefit for detecting actin-related genes and suggest that having actin filaments of mixed composition, containing both mutant and wild-type subunits, presents unique challenges to the cell.
authors.affiliation: Department of Computer Science and Engineering, University of Minnesota, Minneapolis, Minnesota 55455.
authors.forename: Stephanie
authors.initials: S
authors.lastname: DiPrima
authors.affiliation: Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, New York 13210.
authors.forename: Brian
authors.initials: B
authors.lastname: Haarer
authors.affiliation: Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, New York 13210.
authors.forename: Susan
authors.initials: S
authors.lastname: Viggiano
authors.affiliation: Department of Computer Science and Engineering, University of Minnesota, Minneapolis, Minnesota 55455.
authors.forename: Carles
authors.initials: C
authors.lastname: Pons
authors.affiliation: Department of Computer Science and Engineering, University of Minnesota, Minneapolis, Minnesota 55455.
authors.forename: Chad L
authors.initials: CL
authors.lastname: Myers
authors.affiliation: Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, New York 13210 ambergd@upstate.edu.
authors.forename: David C
authors.initials: DC
authors.lastname: Amberg
mesh_terms: D000199:Actins / Q000235:genetics*; D000409:Alanine; D000483:Alleles; D005656:Fungal Proteins / Q000235:genetics*; D005800:Genes, Fungal; D006579:Heterozygote; D008856:Microscopy, Fluorescence; D008958:Models, Molecular; D009154:Mutation; D015003:Yeasts / Q000235:genetics*
chemical_list: D000199:Actins; D005656:Fungal Proteins; D000409:Alanine
keywords: actin; complex heterozygosity; cytoskeleton; genetic network; myosin