scholarly journals Identification and functional analysis of the essential and regulatory light chains of the only type II myosin Myo1p in Saccharomyces cerevisiae

2004 ◽  
Vol 165 (6) ◽  
pp. 843-855 ◽  
Author(s):  
Jianying Luo ◽  
Elizabeth A. Vallen ◽  
Christopher Dravis ◽  
Serguei E. Tcheperegine ◽  
Becky Drees ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Point Mutation ◽  
Light Chain ◽  
Type Ii ◽  
Actin Ring ◽  
Major Function ◽  
Regulatory Light Chains ◽  
Essential Light Chain ◽  
Type V ◽  
Type Ii Myosin

Cytokinesis in Saccharomyces cerevisiae involves coordination between actomyosin ring contraction and septum formation and/or targeted membrane deposition. We show that Mlc1p, a light chain for Myo2p (type V myosin) and Iqg1p (IQGAP), is the essential light chain for Myo1p, the only type II myosin in S. cerevisiae. However, disruption or reduction of Mlc1p–Myo1p interaction by deleting the Mlc1p binding site on Myo1p or by a point mutation in MLC1, mlc1-93, did not cause any obvious defect in cytokinesis. In contrast, a different point mutation, mlc1-11, displayed defects in cytokinesis and in interactions with Myo2p and Iqg1p. These data suggest that the major function of the Mlc1p–Myo1p interaction is not to regulate Myo1p activity but that Mlc1p may interact with Myo1p, Iqg1p, and Myo2p to coordinate actin ring formation and targeted membrane deposition during cytokinesis. We also identify Mlc2p as the regulatory light chain for Myo1p and demonstrate its role in Myo1p ring disassembly, a function likely conserved among eukaryotes.

Increased Chitin Synthesis in Response to Type II Myosin Deficiency in Saccharomyces cerevisiae

2000 ◽  
Vol 3 (1) ◽  
pp. 20-25 ◽  
Author(s):  
J.A. Cruz ◽  
R. Garcia ◽  
J.F. Rodriguez-Orengo ◽  
J.R. Rodriguez-Medina
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Type Ii ◽  
Chitin Synthesis ◽  
Type Ii Myosin

scholarly journals Sro7p, a Saccharomyces cerevisiae Counterpart of the Tumor Suppressor l(2)gl Protein, Is Related to Myosins in Function

Genetics ◽  
1998 ◽  
Vol 149 (4) ◽  
pp. 1717-1727 ◽  
Author(s):  
Mitsuhiro Kagami ◽  
Akio Toh-e ◽  
Yasushi Matsui
Keyword(s):  
Tumor Suppressor ◽  
Suppressor Gene ◽  
Small Gtpase ◽  
Genetic Interactions ◽  
Type Ii ◽  
Multicopy Suppressor ◽  
Human Counterpart ◽  
Cold Sensitive ◽  
Type V ◽  
Type Ii Myosin

Abstract Yeast SRO7 was identified as a multicopy suppressor of a defect in Rho3p, a small GTPase that maintains cell polarity. Sro7p and Sro77p, a homologue of Sro7p, possess domains homologous to the protein that are encoded by the Drosophila tumor suppressor gene lethal (2) giant larvae [l(2)gl]. sro7Δ sro77Δ mutants showed a partial defect of organization of the polarized actin cytoskeleton and a cold-sensitive growth phenotype. A human counterpart of l(2)gl could suppress the sro7Δ sro77Δ defect. Similar to the l(2)gl protein, Sro7p formed a complex with Myo1p, a type II myosin. These results indicate that Sro7p and Sro77p are the yeast counterparts of the l(2)gl protein. Our genetic analysis revealed that deletion of SRO7 and SRO77 showed reciprocal suppression with deletion of MYO1 (i.e., the sro7Δ sro77Δ defect was suppressed by myo1Δ and vice versa). In addition, SRO7 showed genetic interactions with MYO2, encoding an essential type V myosin: Overexpression of SRO7 suppressed a defect in MYO2 and, conversely, overexpression of MYO2 suppressed the cold-sensitive phenotype of sro7Δ sro77Δ mutants. These results indicate that Sro7 function is closely related to both Myo1p and Myo2p. We propose a model in which Sro7 function is involved in the targeting of the myosin proteins to their intrinsic pathways.

scholarly journals Role of the Hof1–Cyk3 interaction in cleavage-furrow ingression and primary-septum formation during yeast cytokinesis

2018 ◽  
Vol 29 (5) ◽  
pp. 597-609 ◽  
Author(s):  
Meng Wang ◽  
Ryuichi Nishihama ◽  
Masayuki Onishi ◽  
John R. Pringle
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Functional Significance ◽  
Normal Rate ◽  
Cleavage Furrow ◽  
Type Ii ◽  
Septum Formation ◽  
Primary Septum ◽  
Direct Binding ◽  
Type Ii Myosin

In Saccharomyces cerevisiae, it is well established that Hof1, Cyk3, and Inn1 contribute to septum formation and cytokinesis. Because hof1∆ and cyk3∆ single mutants have relatively mild defects but hof1∆ cyk3∆ double mutants are nearly dead, it has been hypothesized that these proteins contribute to parallel pathways. However, there is also evidence that they interact physically. In this study, we examined this interaction and its functional significance in detail. Our data indicate that the interaction 1) is mediated by a direct binding of the Hof1 SH3 domain to a proline-rich motif in Cyk3; 2) occurs specifically at the time of cytokinesis but is independent of the (hyper)phosphorylation of both proteins that occurs at about the same time; 3) is dispensable for the normal localization of both proteins; 4) is essential for normal primary-septum formation and a normal rate of cleavage-furrow ingression; and 5) becomes critical for growth when either Inn1 or the type II myosin Myo1 (a key component of the contractile actomyosin ring) is absent. The similarity in phenotype between cyk3∆ mutants and mutants specifically lacking the Hof1–Cyk3 interaction suggests that the interaction is particularly important for Cyk3 function, but it may be important for Hof1 function as well.

Type II myosin regulatory light chain relieves auto-inhibition of myosin-heavy-chain function

2000 ◽  
Vol 2 (11) ◽  
pp. 855-858 ◽  
Author(s):  
Naweed I. Naqvi ◽  
Kelvin C. Y. Wong ◽  
Xie Tang ◽  
Mohan K. Balasubramanian
Keyword(s):  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Light Chain ◽  
Regulatory Light Chain ◽  
Myosin Regulatory Light Chain ◽  
Type Ii ◽  
Type Ii Myosin

The distribution and density of ciliary tufts on the siphons of Anodonta cygnea (Mollusca: Bivalvia)

1990 ◽  
Vol 48 (3) ◽  
pp. 518-519
Author(s):  
Wen-lung Wu
Keyword(s):  
Osmium Tetroxide ◽  
Internal Surface ◽  
Mechanical Stimuli ◽  
Type Ii ◽  
Sensory Receptors ◽  
Anodonta Cygnea ◽  
Type Iv ◽  
Sem Study ◽  
Inhalant Siphon ◽  
Type V

The mantle of bivalves has come entirely to enclose the laterally compressed body and the mantle margin has assumed a variety of functions, one of the pricipal ones being sensory. Ciliary tufts, which are probably sensory, have been reported from the mantle and siphons of several bivalves1∽4. Certain regions of the mantle margin are likely to be more or less, sensitive to certain stimuli than others. The inhalant siphon is likely to be particularly sensitive to both chemical and mechanical stimuli, whereas the exhalant siphon will be less sensitive to both. The distribution and density of putative sensory receptors on the in-and ex-halant siphon is compared in this paper.The excised siphons were fixed in glutaraldehyde and osmium tetroxide, the whole procedure of SEM study is recorded in Wu's thesis.Type II cilia cover the tips of tentacles, 6.13um. Type IV and type V cilia are found on the surface of tentacles. Type IV cilia are occasionally present at the tips of tentacles, 8 um long. They are the commonest type on the surface of tentacles. Type VI cilia occor in the internal surface of the inhalant siphon, but are not found on the surface of tentacles, 6.7-10um long.

Functional regions in the essential light chain of smooth muscle myosin as revealed by the mutagenesis approach

2000 ◽  
Vol 267 (20) ◽  
pp. 6151-6157 ◽  
Author(s):  
Sophie Quevillon-Chéruel ◽  
Chantal Janmot ◽  
Muriel Nozais ◽  
Anne-Marie Lompré ◽  
Jean-Jacques Béchet
Keyword(s):  
Smooth Muscle ◽  
Light Chain ◽  
Smooth Muscle Myosin ◽  
Essential Light Chain ◽  
Functional Regions ◽  
Muscle Myosin
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