Adenylate Kinases 1 and 2 Are Part of the Accessory Structures in the Mouse Sperm Flagellum

• Published in: Biology of reproduction Vol. 75; no. 4; pp. 492 - 500
• Main Authors: Cao, Wenlei, Haig-Ladewig, Lisa, Gerton, George L, Moss, Stuart B
• Format: Journal Article
• Language: English
• Published: Madison, WI Society for the Study of Reproduction, Inc 01.10.2006; Society for the Study of Reproduction
• Subjects: 3' Untranslated Regions; 5' Untranslated Regions; Adenylate Kinase - genetics; Adenylate Kinase - metabolism; Animals; Biological and medical sciences; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation, Enzymologic; Isoenzymes - genetics; Isoenzymes - metabolism; Male; Mammalian male genital system; Mice; Mice, Inbred Strains; Mitochondria - metabolism; Molecular Sequence Data; Morphology. Physiology; Organ Specificity; Sperm Motility; Sperm Tail - enzymology; Spermatogenesis - genetics; Spermatogenesis - physiology; Testis - enzymology; Vertebrates: reproduction; Spermatozoa; sperm motility and transport; Motility; Enzyme; Gametogenesis; Spermatogenesis; Transferases; Biological transport; Rodentia; Flagellum; EC 2.7.4.3; sperm; Germinal cell; Vertebrata; Reproduction; Mammalia; Adenylate kinase; Mouse; Animal
• ISSN: 0006-3363; 1529-7268
• DOI: 10.1095/biolreprod.106.053512

Proper sperm function depends on adequate ATP levels. In the mammalian flagellum, ATP is generated in the midpiece by oxidative respiration and in the principal piece by glycolysis. In locations where ATP is rapidly utilized or produced, adenylate kinases (AKs) maintain a constant adenylate energy charge by interconverting stoichiometric amounts of ATP and AMP with two ADP molecules. We previously identified adenylate kinase 1 and 2 (AK1 and AK2) by mass spectrometry as part of a mouse SDS-insoluble flagellar preparation containing the accessory structures (fibrous sheath, outer dense fibers, and mitochondrial sheath). A germ cell-specific cDNA encoding AK1 was characterized and found to contain a truncated 3' UTR and a different 5' UTR compared to the somatic Ak1 mRNA; however, it encoded an identical protein. Ak1 mRNA was upregulated during late spermiogenesis, a time when the flagellum is being assembled. AK1 was first seen in condensing spermatids and was associated with the outer microtubular doublets and outer dense fibers of sperm. This localization would allow the interconversion of ATP and ADP between the fibrous sheath where ATP is produced by glycolysis and the axonemal dynein ATPases where ATP is consumed. Ak2 mRNA was expressed at relatively low levels throughout spermatogenesis, and the protein was localized to the mitochondrial sheath in the sperm midpiece. AK1 and AK2 in the flagellar accessory structures provide a mechanism to buffer the adenylate energy charge for sperm motility.