Mutational analysis of apolipoprotein B mRNA editing enzyme (APOBEC1): structure–function relationships of RNA editing and dimerization
APOBEC1 is the catalytic subunit of an enzyme complex that mediates apolipoprotein (apo) B mRNA editing. It dimerizes in vitro and requires complementation factor(s) for its editing activity. We have performed a systematic analysis of the structure–functional relationship of APOBEC1 by targeted muta...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
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Elsevier
1999-04-01
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| Series: | Journal of Lipid Research |
| Subjects: | |
| Online Access: | http://www.sciencedirect.com/science/article/pii/S0022227520321416 |
| _version_ | 1818934979323756544 |
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| author | Ba-Bie Teng Scott Ochsner Qian Zhang Kizhake V. Soman Paul P. Lau Lawrence Chan |
| author_facet | Ba-Bie Teng Scott Ochsner Qian Zhang Kizhake V. Soman Paul P. Lau Lawrence Chan |
| author_sort | Ba-Bie Teng |
| collection | DOAJ |
| description | APOBEC1 is the catalytic subunit of an enzyme complex that mediates apolipoprotein (apo) B mRNA editing. It dimerizes in vitro and requires complementation factor(s) for its editing activity. We have performed a systematic analysis of the structure–functional relationship of APOBEC1 by targeted mutagenesis of various sequence motifs within the protein. Using in vitro RNA editing assay, we found that basic amino acid clusters at the amino-terminal region R15R16R17 and R33K34, are essential for apoB mRNA editing. Mutation of R15R16R17 to K15K16K17 and mutation of R33K34 simultaneously to A33A34 almost completely abolished in vitro editing activity. The carboxy-terminal region of APOBEC1 contains a leucine-rich motif. Deletion analysis of this region indicates that residues 181 to 210 are important for in vitro apoB mRNA editing. Single amino acid substitutions demonstrate that L182, I185, and L189 are important residues required for normal editing function. Furthermore, the double mutant P190A/P191A also lost >90% of editing activity which suggests that a β turn in this region of the molecule may be essential for proper functioning of APOBEC1. It was suggested that dimerization of APOBEC1 creates an active structure for deamination of apoB mRNA. When we examined the dimerization potential of truncated APOBEC1s using both amino and carboxy termini deletion mutants, we found that amino-terminal deletions up to residue A117 did not impair dimerization activity whereas carboxy-terminal deletions showed diminished dimerization. The systematic and extensive mutagenesis experiments in this study provide information on the role of various sequence motifs identified in APOBEC1 in enzyme catalysis and dimerization.—Teng, B-B., S. Ochsner, Q. Zhang, K. V. Soman, P. P. Lau, and L. Chan. Mutational analysis of apolipoprotein B mRNA editing enzyme (APOBEC1): structure–function relationships of RNA editing and dimerization. J. Lipid Res. 1999. 40: 623–635. |
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| id | doaj.art-8b954dcd6c944eae99e110d96435d559 |
| institution | Directory Open Access Journal |
| issn | 0022-2275 |
| language | English |
| last_indexed | 2024-12-20T05:12:52Z |
| publishDate | 1999-04-01 |
| publisher | Elsevier |
| record_format | Article |
| series | Journal of Lipid Research |
| spelling | doaj.art-8b954dcd6c944eae99e110d96435d5592022-12-21T19:52:14ZengElsevierJournal of Lipid Research0022-22751999-04-01404623635Mutational analysis of apolipoprotein B mRNA editing enzyme (APOBEC1): structure–function relationships of RNA editing and dimerizationBa-Bie Teng0Scott Ochsner1Qian Zhang2Kizhake V. Soman3Paul P. Lau4Lawrence Chan5To whom correspondence should be addressed.; Departments of Medicine Baylor College of Medicine, Houston, TX 77030-3498; Research Center for Human Genetics, Institute of Molecular Medicine, University of Texas-Houston, Houston, TX 77030Departments of Medicine Baylor College of Medicine, Houston, TX 77030-3498Research Center for Human Genetics, Institute of Molecular Medicine, University of Texas-Houston, Houston, TX 77030Departments of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX 77030-3498Departments of Medicine Baylor College of Medicine, Houston, TX 77030-3498Departments of Medicine Baylor College of Medicine, Houston, TX 77030-3498APOBEC1 is the catalytic subunit of an enzyme complex that mediates apolipoprotein (apo) B mRNA editing. It dimerizes in vitro and requires complementation factor(s) for its editing activity. We have performed a systematic analysis of the structure–functional relationship of APOBEC1 by targeted mutagenesis of various sequence motifs within the protein. Using in vitro RNA editing assay, we found that basic amino acid clusters at the amino-terminal region R15R16R17 and R33K34, are essential for apoB mRNA editing. Mutation of R15R16R17 to K15K16K17 and mutation of R33K34 simultaneously to A33A34 almost completely abolished in vitro editing activity. The carboxy-terminal region of APOBEC1 contains a leucine-rich motif. Deletion analysis of this region indicates that residues 181 to 210 are important for in vitro apoB mRNA editing. Single amino acid substitutions demonstrate that L182, I185, and L189 are important residues required for normal editing function. Furthermore, the double mutant P190A/P191A also lost >90% of editing activity which suggests that a β turn in this region of the molecule may be essential for proper functioning of APOBEC1. It was suggested that dimerization of APOBEC1 creates an active structure for deamination of apoB mRNA. When we examined the dimerization potential of truncated APOBEC1s using both amino and carboxy termini deletion mutants, we found that amino-terminal deletions up to residue A117 did not impair dimerization activity whereas carboxy-terminal deletions showed diminished dimerization. The systematic and extensive mutagenesis experiments in this study provide information on the role of various sequence motifs identified in APOBEC1 in enzyme catalysis and dimerization.—Teng, B-B., S. Ochsner, Q. Zhang, K. V. Soman, P. P. Lau, and L. Chan. Mutational analysis of apolipoprotein B mRNA editing enzyme (APOBEC1): structure–function relationships of RNA editing and dimerization. J. Lipid Res. 1999. 40: 623–635.http://www.sciencedirect.com/science/article/pii/S0022227520321416apoBRNA editingAPOBEC1cytidine deaminase |
| spellingShingle | Ba-Bie Teng Scott Ochsner Qian Zhang Kizhake V. Soman Paul P. Lau Lawrence Chan Mutational analysis of apolipoprotein B mRNA editing enzyme (APOBEC1): structure–function relationships of RNA editing and dimerization Journal of Lipid Research apoB RNA editing APOBEC1 cytidine deaminase |
| title | Mutational analysis of apolipoprotein B mRNA editing enzyme (APOBEC1): structure–function relationships of RNA editing and dimerization |
| title_full | Mutational analysis of apolipoprotein B mRNA editing enzyme (APOBEC1): structure–function relationships of RNA editing and dimerization |
| title_fullStr | Mutational analysis of apolipoprotein B mRNA editing enzyme (APOBEC1): structure–function relationships of RNA editing and dimerization |
| title_full_unstemmed | Mutational analysis of apolipoprotein B mRNA editing enzyme (APOBEC1): structure–function relationships of RNA editing and dimerization |
| title_short | Mutational analysis of apolipoprotein B mRNA editing enzyme (APOBEC1): structure–function relationships of RNA editing and dimerization |
| title_sort | mutational analysis of apolipoprotein b mrna editing enzyme apobec1 structure function relationships of rna editing and dimerization |
| topic | apoB RNA editing APOBEC1 cytidine deaminase |
| url | http://www.sciencedirect.com/science/article/pii/S0022227520321416 |
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