Plant heteromeric acetyl-CoA carboxylase (htACCase) catalyzes the first and committed reaction of de novo fatty acid biosynthesis in plastids. Arabidopsis htACCase consists of five subunits: BCCP-1, BCCP-2, BC, alpha-CT, and beta-CT. They were encoded by CAC1-A, CAC1-B, CAC2, CAC3, and accD genes, respectively. The expression of these five genes was studies by real-time RT-PCR and quantitative western analysis. At the mRNA level, CAC1-A, CAC2, CAC3, and accD genes are expressed at a constant molar ratio of 0.5:1.0:0.2:2.0 across all the organs examined, but the expression pattern of CAC1-B is different. At the protein level, there is no correlation in the accumulation among the five subunits;Analyses using different types of non-denaturing PAGE coupled with western blot analysis with subunit-specific antibodies were performed to study the subunit organization in htACCase complex. These results indicate that the Arabidopsis htACCase is a loose complex that readily dissociates. Analyses with reducing and non-reducing SDS-PAGE revealed the occurrence of homodimers of alpha-CT, and of beta-CT held together by disulfide bond(s). The dimerization was unaffected by illumination;Reverse genetics approaches were used to investigate the individual physiological significance of the two paralogous BCCP-coding genes, CAC1-A and CAC1-B. T-DNA knockout mutant analysis showed that disruption of CAC1-A gene results in embryo lethality, but disruption of CAC1-B gene has no discernible phenotype. In situ hybridization showed that CAC1-A and CAC1-B genes were expressed with similar spatial and temporal patterns during embryo development. This indicates that BCCP-1 and BCCP-2 have non-equivalent physiological roles. CAC1-A antisense plants showed a range of morphological changes, which correlate with the reduction in BCCP-1 accumulation. Similar to CAC1-A, disruption of CAC3 gene also results in the embryo lethal phenotype. The reduction of BCCP-1 results in reduced amount of fatty acids (on per plant basis) in leaves and seeds, but doesn't affect the fatty acid composition. In contrast, loss of BCCP-2 changes neither the amount nor the composition of seed fatty acids. These observations suggest that BCCP-1 is important for htACCase activity in planta, but BCCP-2 is dispensable. Further investigation is needed to elucidate the mechanism of the unidirectional redundancy between BCCP-1 and BCCP-2 subunits.
","abstract_html":"<p>Plant heteromeric acetyl-CoA carboxylase (htACCase) catalyzes the first and committed reaction of de novo fatty acid biosynthesis in plastids. Arabidopsis htACCase consists of five subunits: BCCP-1, BCCP-2, BC, alpha-CT, and beta-CT. They were encoded by CAC1-A, CAC1-B, CAC2, CAC3, and accD genes, respectively. The expression of these five genes was studies by real-time RT-PCR and quantitative western analysis. At the mRNA level, CAC1-A, CAC2, CAC3, and accD genes are expressed at a constant molar ratio of 0.5:1.0:0.2:2.0 across all the organs examined, but the expression pattern of CAC1-B is different. At the protein level, there is no correlation in the accumulation among the five subunits;Analyses using different types of non-denaturing PAGE coupled with western blot analysis with subunit-specific antibodies were performed to study the subunit organization in htACCase complex. These results indicate that the Arabidopsis htACCase is a loose complex that readily dissociates. Analyses with reducing and non-reducing SDS-PAGE revealed the occurrence of homodimers of alpha-CT, and of beta-CT held together by disulfide bond(s). The dimerization was unaffected by illumination;Reverse genetics approaches were used to investigate the individual physiological significance of the two paralogous BCCP-coding genes, CAC1-A and CAC1-B. T-DNA knockout mutant analysis showed that disruption of CAC1-A gene results in embryo lethality, but disruption of CAC1-B gene has no discernible phenotype. In situ hybridization showed that CAC1-A and CAC1-B genes were expressed with similar spatial and temporal patterns during embryo development. This indicates that BCCP-1 and BCCP-2 have non-equivalent physiological roles. CAC1-A antisense plants showed a range of morphological changes, which correlate with the reduction in BCCP-1 accumulation. Similar to CAC1-A, disruption of CAC3 gene also results in the embryo lethal phenotype. The reduction of BCCP-1 results in reduced amount of fatty acids (on per plant basis) in leaves and seeds, but doesn't affect the fatty acid composition. In contrast, loss of BCCP-2 changes neither the amount nor the composition of seed fatty acids. These observations suggest that BCCP-1 is important for htACCase activity in planta, but BCCP-2 is dispensable. Further investigation is needed to elucidate the mechanism of the unidirectional redundancy between BCCP-1 and BCCP-2 subunits.</p>","abstract_has_math":false,"creators":["Li, Xu"],"institution":null,"degree_name":"Doctor of Philosophy","degree_level":"dissertation","degree_discipline":null,"degree_department":"Roy J. Carver Department of Biochemistry, Biophysics and Molecular Biology (LAS)","school":null,"contributors":[],"advisors":["Basil J. Nikolau"],"committee_chairs":[],"committee_members":[],"year":2005,"date_issued":"2005-01-01","date_published":"2005-01-01","updated_at":"2026-07-24T02:38:46Z","subjects":[],"languages":["en"],"rights":[],"rights_urls":[],"identifier_entries":[{"key":"dc:identifier.doi","label":"DOI","values":["https://doi.org/10.31274/rtd-180813-12633"],"render_values":[{"text":"https://doi.org/10.31274/rtd-180813-12633","href":"https://doi.org/10.31274/rtd-180813-12633","code":true}]},{"key":"dc:identifier","label":"Identifier","values":["archive/lib.dr.iastate.edu/rtd/1753/"],"render_values":[{"text":"archive/lib.dr.iastate.edu/rtd/1753/","href":null,"code":true}]}]},"links":{"outbound_url":"https://dr.lib.iastate.edu/handle/20.500.12876/71353","outbound_label":"Repository record","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.advisor","label":"Advisor","values":["Basil J. 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Arabidopsis htACCase consists of five subunits: BCCP-1, BCCP-2, BC, alpha-CT, and beta-CT. They were encoded by CAC1-A, CAC1-B, CAC2, CAC3, and accD genes, respectively. The expression of these five genes was studies by real-time RT-PCR and quantitative western analysis. At the mRNA level, CAC1-A, CAC2, CAC3, and accD genes are expressed at a constant molar ratio of 0.5:1.0:0.2:2.0 across all the organs examined, but the expression pattern of CAC1-B is different. At the protein level, there is no correlation in the accumulation among the five subunits;Analyses using different types of non-denaturing PAGE coupled with western blot analysis with subunit-specific antibodies were performed to study the subunit organization in htACCase complex. These results indicate that the Arabidopsis htACCase is a loose complex that readily dissociates. Analyses with reducing and non-reducing SDS-PAGE revealed the occurrence of homodimers of alpha-CT, and of beta-CT held together by disulfide bond(s). The dimerization was unaffected by illumination;Reverse genetics approaches were used to investigate the individual physiological significance of the two paralogous BCCP-coding genes, CAC1-A and CAC1-B. T-DNA knockout mutant analysis showed that disruption of CAC1-A gene results in embryo lethality, but disruption of CAC1-B gene has no discernible phenotype. In situ hybridization showed that CAC1-A and CAC1-B genes were expressed with similar spatial and temporal patterns during embryo development. This indicates that BCCP-1 and BCCP-2 have non-equivalent physiological roles. CAC1-A antisense plants showed a range of morphological changes, which correlate with the reduction in BCCP-1 accumulation. Similar to CAC1-A, disruption of CAC3 gene also results in the embryo lethal phenotype. The reduction of BCCP-1 results in reduced amount of fatty acids (on per plant basis) in leaves and seeds, but doesn't affect the fatty acid composition. In contrast, loss of BCCP-2 changes neither the amount nor the composition of seed fatty acids. These observations suggest that BCCP-1 is important for htACCase activity in planta, but BCCP-2 is dispensable. Further investigation is needed to elucidate the mechanism of the unidirectional redundancy between BCCP-1 and BCCP-2 subunits.
"]},{"key":"dc:format.mimetype","label":"Dc Format Mimetype","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["Functional and expression analysis of heteromeric acetyl-CoA carboxylase subunit genes of Arabidopsis"]}]}],"canonical_facts":{"dc:contributor.advisor":["Basil J. Nikolau"],"dc:contributor.department":["Roy J. Carver Department of Biochemistry, Biophysics and Molecular Biology (LAS)"],"dc:creator":["Li, Xu"],"dc:date":["2018-08-24T21:44:12.000"],"dc:date.accessioned":["2020-06-30T08:00:42Z"],"dc:date.available":["2020-06-30T08:00:42Z"],"dc:date.issued":["2005-01-01"],"dc:description.abstract":["Plant heteromeric acetyl-CoA carboxylase (htACCase) catalyzes the first and committed reaction of de novo fatty acid biosynthesis in plastids. Arabidopsis htACCase consists of five subunits: BCCP-1, BCCP-2, BC, alpha-CT, and beta-CT. They were encoded by CAC1-A, CAC1-B, CAC2, CAC3, and accD genes, respectively. The expression of these five genes was studies by real-time RT-PCR and quantitative western analysis. At the mRNA level, CAC1-A, CAC2, CAC3, and accD genes are expressed at a constant molar ratio of 0.5:1.0:0.2:2.0 across all the organs examined, but the expression pattern of CAC1-B is different. At the protein level, there is no correlation in the accumulation among the five subunits;Analyses using different types of non-denaturing PAGE coupled with western blot analysis with subunit-specific antibodies were performed to study the subunit organization in htACCase complex. These results indicate that the Arabidopsis htACCase is a loose complex that readily dissociates. Analyses with reducing and non-reducing SDS-PAGE revealed the occurrence of homodimers of alpha-CT, and of beta-CT held together by disulfide bond(s). The dimerization was unaffected by illumination;Reverse genetics approaches were used to investigate the individual physiological significance of the two paralogous BCCP-coding genes, CAC1-A and CAC1-B. T-DNA knockout mutant analysis showed that disruption of CAC1-A gene results in embryo lethality, but disruption of CAC1-B gene has no discernible phenotype. In situ hybridization showed that CAC1-A and CAC1-B genes were expressed with similar spatial and temporal patterns during embryo development. This indicates that BCCP-1 and BCCP-2 have non-equivalent physiological roles. CAC1-A antisense plants showed a range of morphological changes, which correlate with the reduction in BCCP-1 accumulation. Similar to CAC1-A, disruption of CAC3 gene also results in the embryo lethal phenotype. The reduction of BCCP-1 results in reduced amount of fatty acids (on per plant basis) in leaves and seeds, but doesn't affect the fatty acid composition. In contrast, loss of BCCP-2 changes neither the amount nor the composition of seed fatty acids. These observations suggest that BCCP-1 is important for htACCase activity in planta, but BCCP-2 is dispensable. Further investigation is needed to elucidate the mechanism of the unidirectional redundancy between BCCP-1 and BCCP-2 subunits.
"],"dc:format.mimetype":["application/pdf"],"dc:identifier":["archive/lib.dr.iastate.edu/rtd/1753/"],"dc:identifier.doi":["https://doi.org/10.31274/rtd-180813-12633"],"dc:identifier.uri":["https://dr.lib.iastate.edu/handle/20.500.12876/71353"],"dc:language.iso":["en"],"dc:title":["Functional and expression analysis of heteromeric acetyl-CoA carboxylase subunit genes of Arabidopsis"],"dc:type":["dissertation"],"thesis:degree_level":["dissertation"],"thesis:degree_name":["Doctor of Philosophy"]},"updated_at":"2026-07-24T02:38:46Z"}