Change of subunit composition of mitochondrial complex II (succinate–ubiquinone reductase/quinol–fumarate reductase) in Ascaris suum during the migration in the experimental host

• Published in: Parasitology international Vol. 57; no. 1; pp. 54 - 61
• Main Authors: Iwata, Fumiko, Shinjyo, Noriko, Amino, Hisako, Sakamoto, Kimitoshi, Islam, M. Khyrul, Tsuji, Naotoshi, Kita, Kiyoshi
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier Ireland Ltd 01-03-2008
• Subjects: Animal Migration - physiology; Animals; Antibodies, Helminth - analysis; Antibodies, Helminth - metabolism; Ascariasis - enzymology; Ascariasis - parasitology; Ascaris suum - enzymology; Ascaris suum - growth & development; Ascaris suum - physiology; Ascaris suum lung-stage L3 (LL3); Blotting, Western; Complex II; Electron Transport Complex II - analysis; Electron Transport Complex II - chemistry; Electron Transport Complex II - metabolism; Electrophoresis, Polyacrylamide Gel; Gastroenterology and Hepatology; Infectious Disease; Larva - enzymology; Larva - physiology; Mitochondria, Muscle - enzymology; NADH–fumarate reductase; Oxidative stress; Oxidoreductases - analysis; Oxidoreductases - metabolism; Protein Subunits - analysis; Protein Subunits - metabolism; Quinol–fumarate reductase (QFR); Quinone; Quinones - analysis; Rabbits; quinol–fumarate reductase; dUQ; Oxidative stress; adult CybS; CBB; CybS A; flavoprotein subunit; rhodoquinone; Ip; NADH–fumarate reductase; Quinol–fumarate reductase (QFR); decyl UQ; third stage larva; SDH; lung stage L3; CybS L; QFR; UQ; HPLC; adult Fp; CybL; ubiquinone; Complex II; dRQ; BN-PAGE; blue-native polyacrylamide gel electrophoresis; Quinone; large subunit of cytochrome b; CybS; L3; Ascaris suum lung-stage L3 (LL3); Coomassie brilliant blue; Fp; Fp A; iron–sulfur cluster subunit; succinate dehydrogenase; SDS-PAGE; LL3; high performance liquid chromatography; SQR; Fp L; sodium dodecyl sulfate-PAGE; small subunit of cytochrome b; larval Fp; larval CybS; succinate–ubiquinone reductase; RQ; decyl RQ
• ISSN: 1383-5769; 1873-0329
• DOI: 10.1016/j.parint.2007.08.002

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 (∼ 160 nmol/min/mg) than mitochondria of A. suum at other stages (L3: ∼ 80 nmol/min/mg; adult: ∼ 70 nmol/min/mg). Ubiquinone content in LL3 mitochondria was more abundant than rhodoquinone (∼ 1.8 nmol/mg versus ∼ 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 (FpL ) and adult Fp (FpA ) at a ratio of 1:0.56, and that most LL3 CybS subunits were of the adult form (CybSA ). 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.