title: Change of subunit composition of mitochondrial complex II (succinate-ubiquinone reductase/quinol-fumarate reductase) in Ascaris suum during the migration in the experimental host.
abstract: The mitochondrial metabolic pathway of the parasitic nematode Ascaris suum changes dramatically during its life cycle, to adapt to changes in the environmental oxygen concentration. We previously showed that A. suum mitochondria express stage-specific isoforms of complex II (succinate-ubiquinone reductase: SQR/quinol-fumarate reductase: QFR). The flavoprotein (Fp) and small subunit of cytochrome b (CybS) in adult complex II differ from those of infective third stage larval (L3) complex II. However, there is no difference in the iron-sulfur cluster (Ip) or the large subunit of cytochrome b (CybL) between adult and L3 isoforms of complex II. In the present study, to clarify the changes that occur in the respiratory chain of A. suum larvae during their migration in the host, we examined enzymatic activity, quinone content and complex II subunit composition in mitochondria of lung stage L3 (LL3) A. suum larvae. LL3 mitochondria showed higher QFR activity ( approximately 160 nmol/min/mg) than mitochondria of A. suum at other stages (L3: approximately 80 nmol/min/mg; adult: approximately 70 nmol/min/mg). Ubiquinone content in LL3 mitochondria was more abundant than rhodoquinone ( approximately 1.8 nmol/mg versus approximately 0.9 nmol/mg). Interestingly, the results of two-dimensional bule-native/sodium dodecyl sulfate polyacrylamide gel electrophoresis analyses showed that LL3 mitochondria contained larval Fp (Fp(L)) and adult Fp (Fp(A)) at a ratio of 1:0.56, and that most LL3 CybS subunits were of the adult form (CybS(A)). This clearly indicates that the rearrangement of complex II begins with a change in the isoform of the anchor CybS subunit, followed by a similar change in the Fp subunit.
authors.affiliation: Department of Biomedical Chemistry, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113 0033, Japan.
authors.forename: Fumiko
authors.initials: F
authors.lastname: Iwata
authors.forename: Noriko
authors.initials: N
authors.lastname: Shinjyo
authors.forename: Hisako
authors.initials: H
authors.lastname: Amino
authors.forename: Kimitoshi
authors.initials: K
authors.lastname: Sakamoto
authors.forename: M Khyrul
authors.initials: MK
authors.lastname: Islam
authors.forename: Naotoshi
authors.initials: N
authors.lastname: Tsuji
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Kita
mesh_terms: D025041:Animal Migration / Q000502:physiology; D000818:Animals; D000909:Antibodies, Helminth / Q000032:analysis / Q000378:metabolism; D001196:Ascariasis / Q000201:enzymology / Q000469:parasitology*; D017165:Ascaris suum / Q000201:enzymology* / Q000254:growth & development / Q000502:physiology; D015153:Blotting, Western; D042963:Electron Transport Complex II / Q000032:analysis / Q000737:chemistry / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D007814:Larva / Q000201:enzymology / Q000502:physiology; D008931:Mitochondria, Muscle / Q000201:enzymology*; D010088:Oxidoreductases / Q000032:analysis / Q000378:metabolism; D021122:Protein Subunits / Q000032:analysis / Q000378:metabolism; D011809:Quinones / Q000032:analysis; D011817:Rabbits
chemical_list: D000909:Antibodies, Helminth; D021122:Protein Subunits; D011809:Quinones; D010088:Oxidoreductases; D042963:Electron Transport Complex II; C424907:quinol fumarate reductase