International Journal of Molecular Sciences (Apr 2020)

Structural Characterization of an ACP from <i>Thermotoga maritima</i>: Insights into Hyperthermal Adaptation

  • Yeongjoon Lee,
  • Ahjin Jang,
  • Min-Cheol Jeong,
  • Nuri Park,
  • Jungwoo Park,
  • Woo Cheol Lee,
  • Chaejoon Cheong,
  • Yangmee Kim

DOI
https://doi.org/10.3390/ijms21072600
Journal volume & issue
Vol. 21, no. 7
p. 2600

Abstract

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Thermotoga maritima, a deep-branching hyperthermophilic bacterium, expresses an extraordinarily stable Thermotoga maritima acyl carrier protein (Tm-ACP) that functions as a carrier in the fatty acid synthesis system at near-boiling aqueous environments. Here, to understand the hyperthermal adaptation of Tm-ACP, we investigated the structure and dynamics of Tm-ACP by nuclear magnetic resonance (NMR) spectroscopy. The melting temperature of Tm-ACP (101.4 °C) far exceeds that of other ACPs, owing to extensive ionic interactions and tight hydrophobic packing. The D59 residue, which replaces Pro/Ser of other ACPs, mediates ionic clustering between helices III and IV. This creates a wide pocket entrance to facilitate the accommodation of long acyl chains required for hyperthermal adaptation of the T. maritima cell membrane. Tm-ACP is revealed to be the first ACP that harbor an amide proton hyperprotected against hydrogen/deuterium exchange for I15. The hydrophobic interactions mediated by I15 appear to be the key driving forces of the global folding process of Tm-ACP. Our findings provide insights into the structural basis of the hyperthermal adaptation of ACP, which might have allowed T. maritima to survive in hot ancient oceans.

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