Analysis of Nanoarchaeum equitans genome and proteome composition: indications for hyperthermophilic and parasitic adaptation
IR@IICB: CSIR-Indian Institute of Chemical Biology, Kolkata
View Archive Info| Field | Value | |
| Title |
Analysis of Nanoarchaeum equitans genome and proteome
composition: indications for hyperthermophilic and parasitic
adaptation
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| Creator |
Das, Sabyasachi
Paul, Sandip Bag, Sumit K Dutta, Chitra |
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| Subject |
Molecular & Human Genetics
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| Description |
Background: Nanoarchaeum equitans, the only known hyperthermophilic archaeon exhibiting parasitic life
style, has raised some new questions about the evolution of the Archaea and provided a model of choice
to study the genome landmarks correlated with thermo-parasitic adaptation. In this context, we have
analyzed the genome and proteome composition of N. equitans and compared the same with those of
other mesophiles, hyperthermophiles and obligatory host-associated organisms.
Results: Analysis of nucleotide, codon and amino acid usage patterns in N. equitans indicates the presence
of distinct selective constraints, probably due to its adaptation to a thermo-parasitic life-style. Among the
conspicuous characteristics featuring its hyperthermophilic adaptation are overrepresentation of purine
bases in protein coding sequences, higher GC-content in tRNA/rRNA sequences, distinct synonymous
codon usage, enhanced usage of aromatic and positively charged residues, and decreased frequencies of
polar uncharged residues, as compared to those in mesophilic organisms. Positively charged amino acid
residues are relatively abundant in the encoded gene-products of N. equitans and other hyperthermophiles,
which is reflected in their isoelectric point distribution. Pairwise comparison of 105 orthologous protein
sequences shows a strong bias towards replacement of uncharged polar residues of mesophilic proteins
by Lys/Arg, Tyr and some hydrophobic residues in their Nanoarchaeal orthologs. The traits potentially
attributable to the symbiotic/parasitic life-style of the organism include the presence of apparently weak
translational selection in synonymous codon usage and a marked heterogeneity in membrane-associated
proteins, which may be important for N. equitans to interact with the host and hence, may help the
organism to adapt to the strictly host-associated life style. Despite being strictly host-dependent, N.
equitans follows cost minimization hypothesis.
Conclusion: The present study reveals that the genome and proteome composition of N. equitans are
marked with the signatures of dual adaptation – one to high temperature and the other to obligatory
parasitism. While the analysis of nucleotide/amino acid preferences in N. equitans offers an insight into the
molecular strategies taken by the archaeon for thermo-parasitic adaptation, the comparative study of the
compositional characteristics of mesophiles, hyperthermophiles and obligatory host-associated organisms
demonstrates the generality of such strategies in the microbial world.
Published: 25 July 2006
BMC Genomics 2006, 7:186 doi:10.1186/1471-2164-7-186
Received: 30 May 2006
Accepted: 25 July 2006
This article is available from: http://www.biomedcentral.com/1471-2164/7/186
© 2006 Das et al; licensee BioMed Central Ltd.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0),
which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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| Date |
2006
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| Type |
Article
PeerReviewed |
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| Format |
application/pdf
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| Identifier |
http://www.eprints.iicb.res.in/434/1/BMC_GENOMICS%2C_7(186)%2C[58].pdf
Das, Sabyasachi and Paul, Sandip and Bag, Sumit K and Dutta, Chitra (2006) Analysis of Nanoarchaeum equitans genome and proteome composition: indications for hyperthermophilic and parasitic adaptation. BMC Genomics, 7 (186). pp. 1-16. |
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| Relation |
htpp://dx.doi.org/10.1186/1471-2164-7-186
http://www.eprints.iicb.res.in/434/ |
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