Stable and dynamic axes of polarity use distinct formin isoforms in budding yeast.
Bud growth in yeast is guided by myosin-driven delivery of secretory vesicles from the mother cell to the bud. We find transport occurs along two sets of actin cables assembled by two formin isoforms. The Bnr1p formin assembles cables that radiate from the bud neck into the mother, providing a stable mother-bud axis. These cables also depend on septins at the neck and are required for efficient transport from the mother to the bud. The Bni1p formin assembles cables that line the bud cortex and target vesicles to varying locations in the bud. Loss of these cables results in morphological defects as vesicles accumulate at the neck. Assembly of these cables depends on continued polarized secretion, suggesting vesicular transport provides a positive feedback signal for Bni1p activation, possibly by rho-proteins. By coupling different formin isoforms to unique cortical landmarks, yeast uses common cytoskeletal elements to maintain stable and dynamic axes in the same cell.
Pruyne
David
D
Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853-2703, USA.
Gao
Lina
L
Bi
Erfei
E
Bretscher
Anthony
A
D000199:Actins / Q000737:chemistry; D001692:Biological Transport; D019521:Body Patterning; D003598:Cytoskeletal Proteins / Q000502:physiology*; D003599:Cytoskeleton / Q000378:metabolism; D005838:Genotype; D005982:Glutathione Transferase / Q000378:metabolism; D008840:Microfilament Proteins / Q000502:physiology*; D024701:Myosin Type V / Q000737:chemistry; D010957:Plasmids / Q000378:metabolism; D020033:Protein Isoforms; D011721:Pyrenes / Q000737:chemistry; D011994:Recombinant Proteins / Q000737:chemistry; D012441:Saccharomyces cerevisiae / Q000502:physiology*; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000502:physiology*; D013696:Temperature; D013997:Time Factors
D000199:Actins; C106463:BNR1 protein, S cerevisiae; C105191:Bni1 protein, S cerevisiae; D003598:Cytoskeletal Proteins; D008840:Microfilament Proteins; D020033:Protein Isoforms; D011721:Pyrenes; D011994:Recombinant Proteins; D029701:Saccharomyces cerevisiae Proteins; C030984:pyrene; D005982:Glutathione Transferase; D024701:Myosin Type V