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Published on: March 10, 2021
MHC-IIB filament assembly and cellular localization are governed by the rod net charge
Michael Rosenberg1, Ravid Straussman, Ami Ben-Ya'acov
1Department of Biochemistry, Faculty of Medicine, The Hebrew University, Jerusalem, Israel.
Background:
Actin-dependent myosin II molecular motors form an integral part of the cell cytoskeleton. Myosin II molecules contain a long coiled-coil rod that mediates filament assembly required for myosin II to exert its full activity. The exact mechanisms orchestrating filament assembly are not fully understood.
Methodology/Principal Findings:
Here we examine mechanisms controlling filament assembly of non-muscle myosin IIB heavy chain (MHC-IIB). We show that in vitro the entire C-terminus region of net positive charge, found in myosin II rods, is important for self-assembly of MHC-IIB fragments. In contrast, no particular sequences in the rod region with net negative charge were identified as important for self-assembly, yet a minimal area from this region is necessary. Proper paracrystal formation by MHC-IIB fragments requires the 196aa charge periodicity along the entire coiled-coil region. In vivo, in contrast to self-assembly in vitro, negatively-charged regions of the coiled-coil were found to play an important role by controlling the intracellular localization of native MHC-IIB. The entire positively-charged region is also important for intracellular localization of native MHC-IIB.
Conclusions/Significance:
A correct distribution of positive and negative charges along myosin II rod is a necessary component in proper filament assembly and intracellular localization of MHC-IIB.
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