Plants have two respiratory electron transport chains from ubiquinone to oxygen: the cytochrome c pathway and the alternative pathway. The former is common to all eukaryotes, while the latter is found in plants and some lower eukaryotes, but not mammals. A distinct feature of the alternative pathway is that only one protein, alternative oxidase (AOX), is involved in transport of electrons from ubiquinone directly to oxygen. The alternative pathway does not generate a transmembrane potential in contrast to the cytochrome c pathway. Because of this seemingly """"""""wasteful"""""""" property, the biological function of the alternative pathway has long been an enigma. Although, the cDNAs for AOX have been cloned from a number of plants, little is known about its function. To further study the biological function of AOX, transgenic potato plants constitutively overexpressing the enzyme were created in our laboratory. Their phenotype resembled that of the wild type plants, although there was about a two-fold increase in the capacity of the alternative pathway. However, a new AOX band could be seen on the Western blots of total mitochondrial protein. The band migrated about 1kD slower than the doublet of bands representing AOX in leaves of the normal plants and was present in much higher concentrations. One of the explanations for this phenomenon could be that the upper band represents a precursor for the faster migrating AOX doublet. The overexpressing plants may accumulate the precursor due to saturation of a putative processing/modifying system by a vast excess of AOX protein. The precursor could be processed at the N-terminus, C-terminus and/or modified to produce the faster migrating AOX bands. We are currently using MALDI-MS and peptide mass mapping to investigate the structure of this isoform of AOX.

Agency
National Institute of Health (NIH)
Institute
National Center for Research Resources (NCRR)
Type
Biotechnology Resource Grants (P41)
Project #
5P41RR000480-27
Application #
5220575
Study Section
Project Start
Project End
Budget Start
Budget End
Support Year
27
Fiscal Year
1996
Total Cost
Indirect Cost
Peri, S P; Bhadti, V S; Somerville-Armstrong, K S et al. (1999) Affinity reagents for cross-linking hemoglobin: bis(phenoxycarbonylethyl)phosphinic acid (BPCEP) and bis(3-nitrophenoxycarbonylethyl)phosphinic acid (BNCEP). Hemoglobin 23:1-20
Chen, H M; Sood, R; Hosmane, R S (1999) An efficient, short synthesis and potent anti-hepatitis B viral activity of a novel ring-expanded purine nucleoside analogue containing a 5:7-fused, planar, aromatic, imidazo[4,5-e][1,3]diazepine ring system. Nucleosides Nucleotides 18:331-5
Bretner, M; Beckett, T D; Sood, R K et al. (1999) Substrate/inhibition studies of bacteriophage T7 RNA polymerase with the 5'-triphosphate derivative of a ring-expanded ('fat') nucleoside possessing potent antiviral and anticancer activities. Bioorg Med Chem 7:2931-6
Agasimundin, Y S; Mumper, M W; Hosmane, R S (1998) Inhibitors of glycogen phosphorylase b: synthesis, biochemical screening, and molecular modeling studies of novel analogues of hydantocidin. Bioorg Med Chem 6:911-23
Hosmane, R S; Peri, S P; Bhadti, V S et al. (1998) Bis[2-(4-carboxyphenoxy)carbonylethyl]phosphinic acid (BCCEP): a novel affinity reagent for the beta-cleft modification of human hemoglobin. Bioorg Med Chem 6:767-83
Rajappan, V P; Hosmane, R S (1998) Analogues of azepinomycin as inhibitors of guanase. Nucleosides Nucleotides 17:1141-51
Hosmane, R S; Hong, M (1997) How important is the N-3 sugar moiety in the tight-binding interaction of coformycin with adenosine deaminase? Biochem Biophys Res Commun 236:88-93
Lopez-Lara, I M; Orgambide, G; Dazzo, F B et al. (1993) Characterization and symbiotic importance of acidic extracellular polysaccharides of Rhizobium sp. strain GRH2 isolated from acacia nodules. J Bacteriol 175:2826-32
Watson, J T; Kayganich, K (1989) Novel sample preparation for analysis by electron capture negative ionization mass spectrometry. Biochem Soc Trans 17:254-7
Kassel, D B; Kayganich, K A; Watson, J T et al. (1988) Utility of ion source pretreatment with chlorine-containing compounds for enhanced performance in gas chromatography/negative ionization mass spectrometry. Anal Chem 60:911-7

Showing the most recent 10 out of 11 publications