Regulation of Dictyostelium Myosin I and II

• Published in: BBA - General Subjects 2001-03, Vol.1525 (3), p.245-261
• Main Authors: de la Roche, Marc A., Côté, Graham P.
• Format: Article
• Language: English
• Subjects: Actin Cytoskeleton - metabolism; Actins - metabolism; Animals; Calcium-Calmodulin-Dependent Protein Kinases - metabolism; Dictyostelium; Dictyostelium - genetics; Dictyostelium - metabolism; Models, Molecular; Myosin I; Myosin II; Myosin II heavy chain kinase; Myosins - genetics; Myosins - metabolism; p21-activated kinase; Protein Isoforms - metabolism; Protozoan Proteins; Signal Transduction; src Homology Domains
• ISSN: 0304-4165; 0006-3002; 1872-8006
• DOI: 10.1016/S0304-4165(01)00110-6

Dictyostelium expresses 12 different myosins, including seven single-headed myosins I and one conventional two-headed myosin II. In this review we focus on the signaling pathways that regulate Dictyostelium myosin I and myosin II. Activation of myosin I is catalyzed by a Cdc42/Rac-stimulated myosin I heavy chain kinase that is a member of the p21-activated kinase (PAK) family. Evidence that myosin I is linked to the Arp2/3 complex suggests that pathways that regulate myosin I may also influence actin filament assembly. Myosin II activity is stimulated by a cGMP-activated myosin light chain kinase and inhibited by myosin heavy chain kinases (MHCKs) that block bipolar filament assembly. Known MHCKs include MHCK A and MHCK B, which have a novel type of kinase catalytic domain joined to a WD repeat domain, and MHC-protein kinase C (PKC), which contains both diacylglycerol kinase and PKC-related protein kinase catalytic domains. A Dictyostelium PAK (PAKa) acts indirectly to promote myosin II filament formation, suggesting that the MHCKs may be indirectly regulated by Rac GTPases.