Characterisation of the myosin light chain kinase (MLCK) gene of Locusta migratoria and the encoded MLCK

• Published in: Insect molecular biology 2024-08, Vol.33 (4), p.338-349
• Main Authors: Wei, Miao, Zhang, Ning, Li, Xiang‐dong
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Animals; Calcium ions; Calmodulin; Exons; Flight muscle; insect; Insect Proteins - genetics; Insect Proteins - metabolism; Insects; Isoforms; Kinases; Locusta migratoria; Locusta migratoria - enzymology; Locusta migratoria - genetics; Locusts; Muscle contraction; Muscles; Muscles - metabolism; Muscular function; Myosin; Myosin-light-chain kinase; Myosin-Light-Chain Kinase - genetics; Myosin-Light-Chain Kinase - metabolism; phosphorylation; Phylogeny; regulatory light chain; Sf9 Cells; Vertebrates
• ISSN: 0962-1075; 1365-2583; 1365-2583
• DOI: 10.1111/imb.12902

Myosin light chain kinase (MLCK) is a dedicated kinase of myosin regulatory light chain (RLC), playing an essential role in the regulation of muscle contraction and cell motility. Much of the knowledge about MLCK comes from the study of vertebrate MLCK, and little is known about insect MLCK. Here, we identified the single MLCK gene in the locust Locusta migratoria, which spans over 1400 kb, includes 62 exons and accounts for at least five transcripts. We found that the five distinct transcripts of the locust MLCK gene are expressed in a tissue‐specific manner, including three muscle‐specific isoforms and two generic isoforms. To characterise the kinase activity of locust MLCK, we recombinantly expressed LmMLCK‐G, the smallest locust MLCK isoform, in insect Sf9 cells. We demonstrated that LmMLCK‐G is a Ca2+/calmodulin‐dependent kinase that specifically phosphorylates serine 50 of locust muscle myosin RLC (LmRLC). Additionally, we found that almost all LmRLC molecules in the flight muscle and the hindleg muscles of adult locusts are phosphorylated. Locust has a single myosin light chain kinase (MLCK) gene that encodes at least five isoforms of locust MLCK (LmMLCK). LmMLCK is a Ca2+/CaM‐dependent kinase that phosphorylates serine 50 of locust muscle myosin regulatory light chain (LmRLC). LmRLCs in the flight muscle and the hindleg jump muscle of locust are in a phosphorylated state.