Characterization of the cold-adapted alpha-tubulin from the psychrophilic ciliate Euplotes focardii |
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Authors: | Pucciarelli Sandra Miceli Cristina |
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Institution: | Dipartimento di Biologia Molecolare, Cellulare, Animale, Università di Camerino, Via F. Camerini 5, 62032 Camerino (MC), Italy. |
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Abstract: | Tubulin dimers of psychrophilic organisms can polymerize into microtubules at temperatures below 4 degrees C, at which non-cold-adapted microtubules disassemble. This capacity requires specificities in the structure and/or in the posttranslational modifications of the tubulin subunits. A contribution to the knowledge of these specificities was provided by the finding that the amino acid sequence of the alpha-tubulin of the Antarctic ciliate Euplotes focardii contains substitutions that, in addition to conferring an increased hydrophobicity to the molecule, modify sites that are involved in alpha-/alpha-tubulin lateral contacts between protofilaments. At the level of the coding sequence, the alpha-tubulin gene of E. focardii revealed an A+T content appreciably higher than in its homologs in ciliates of temperate waters. This was interpreted as an adaptation to favor DNA strand separation in an environment which is energetically adverse. |
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