Tyrosine phosphorylation/dephosphorylation of myosin II essential light chains of Entamoeba histolytica trophozoites regulates their motility.
Entamoeba histolytica trophozoites dwell in the human intestine as comensals although under still unclear circumstances become invasive and destroy the host tissues. For these activities, trophozoites relay on remarkable motility provided by the cytoskeleton organization. Amebic actin and some of its actin-associated proteins are well known, while components of the myosin II molecule, although predicted from the E. histolytica genome, need biochemical and functional characterization. Recently, an amebic essential light myosin II chain, named EhMLCI, was identified and reported to be phosphorylated in tyrosines. The phosphorylated form of the protein was associated with the soluble assembly incompetent conformation of the heavy myosin chains, while the non-phosphorylated protein was identified with filamentous heavy chains, organized in an assembly competent conformation. It was postulated that EhMLCI tyrosine phosphorylation could act as a negative regulator of myosin II activity by its phosphorylation/dephosphorylation cycles. To test this hypothesis, we constructed an expression vector containing an EhMLCI DNA sequence where two tyrosine residues, with strong probability of phosphorylation and fall within the single EF-hand domain that interacts with the N-terminus of myosin II heavy chains, were replaced by phenylalanines. Transfected trophozoites, expressing the mutant MutEhMLCI protein cannot process it, thereby not incorporated into the phosphorylation/dephosphorylation cycles required for myosin II activity, results in motility defective trophozoites.
Departamento de Biomedicina Molecular, Centro de Investigación y de Estudios Avanzados del IPN, Apartado 14-740, México City 07360, Mexico.
Raúl
R
Bonilla-Moreno
Departamento de Biomedicina Molecular, Centro de Investigación y de Estudios Avanzados del IPN, Apartado 14-740, México City 07360, Mexico.
Eloy-Andrés
EA
Pérez-Yépez
Departamento de Biomedicina Molecular, Centro de Investigación y de Estudios Avanzados del IPN, Apartado 14-740, México City 07360, Mexico.
Nicolás
N
Villegas-Sepúlveda
Departamento de Biomedicina Molecular, Centro de Investigación y de Estudios Avanzados del IPN, Apartado 14-740, México City 07360, Mexico.
Fernando O
FO
Morales
Departamento de Biomedicina Molecular, Centro de Investigación y de Estudios Avanzados del IPN, Apartado 14-740, México City 07360, Mexico. Electronic address: imeza@cinvestav.mx.
Isaura
I
Meza
D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D002633:Chemotaxis; D057899:Cytophagocytosis; D004748:Entamoeba histolytica / Q000502:physiology*; D008124:Locomotion; D009154:Mutation; D018994:Myosin Light Chains / Q000235:genetics / Q000378:metabolism*; D024462:Myosin Type II / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D021381:Protein Transport; D015800:Protozoan Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D053058:Trophozoites; D014443:Tyrosine / Q000378:metabolism*
D018994:Myosin Light Chains; D015800:Protozoan Proteins; D014443:Tyrosine; D024462:Myosin Type II
Deficient phagocytocis and chemotaxis; Essential light myosin II mutants; Motility alterations; Parasitic amebas