Polar residues in a conserved motif spanning helices 1 and 2 are functionally important in the SulP transporter family
| Autor: | Fiona P. Leves, M. Louise Tierney, Susan M. Howitt |
|---|---|
| Rok vydání: | 2008 |
| Předmět: |
Stereochemistry
Anion Transport Proteins Molecular Sequence Data Helix-turn-helix Saccharomyces cerevisiae Biology Biochemistry Protein Structure Secondary Cell membrane Mutant protein medicine Amino Acid Sequence Amino Acids Site-directed mutagenesis Peptide sequence Plant Proteins Conserved motif Sulfates Computational Biology Transporter Cell Biology medicine.anatomical_structure Sulfate Transporters Mutation Polar |
| Zdroj: | The international journal of biochemistrycell biology. 40(11) |
| ISSN: | 1357-2725 |
| Popis: | The SulP family (including the SLC26 family) is a diverse family of anion transporters found in all domains of life, with different members transporting different anions. We used sequence and bioinformatics analysis of helices 1 and 2 of SulP family members to identify a conserved motif, extending the previously defined ‘sulfate transporter motif’. The analysis showed that in addition to being highly conserved in both sequence and spacing, helices 1 and 2 contain a significant number of polar residues and are predicted to be buried within the protein interior, with at least some faces packed closely against other helices. This suggests a significant functional role for this region and we tested this by mutating polar residues in helices 1 and 2 in the sulfate transporter, SHST1. All mutations made, even those removing only a single hydroxyl group, had significant effects on transport. Many mutations abolished transport without affecting plasma membrane expression of the mutant protein, suggesting a functional role for these residues. Different helical faces appear to have different roles, with the most severe effects being localised to two interacting faces of helices 1 and 2. Our results confirm the predicted importance of conserved polar residues in helices 1 and 2 and suggest that transport of sulfate by SHST1 is dependent on a network of polar and aromatic interactions between these two helices. |
| Databáze: | OpenAIRE |
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