DNA alignment and Bayesian trees of partial sequences of COI, COIII and the haemocyanin functional unit f-g of 28 octopod species

Background: Octopods have successfully colonised the world's oceans from the tropics to the poles. Yet, successful persistence in these habitats has required adaptations of their advanced physiological apparatus to compensate impaired oxygen supply. Their oxygen transporter haemocyanin plays a major role in cold tolerance and accordingly has undergone functional modifications to sustain oxygen release at sub-zero temperatures. However, it remains unknown how molecular properties evolved to explain the observed functional adaptations. We thus aimed to assess whether natural selection affected molecular and structural properties of haemocyanin that explains temperature adaptation in octopods.Results: Analysis of 239 partial sequences of the haemocyanin functional units (FU) f and g of 28 octopod species of polar, temperate, subtropical and tropical origin revealed natural selection was acting primarily on charge properties of surface residues. Polar octopods contained haemocyanins with higher net surface charge due to decreased glutamic acid content and higher numbers of basic amino acids. Within the analysed partial sequences, positive selection was present at site 2545, positioned between the active copper binding centre and the FU g surface. At this site, methionine was the dominant amino acid in polar octopods and leucine was dominant in tropical octopods. Sites directly involved in oxygen binding or quaternary interactions were highly conserved within the analysed sequence.Conclusions: This study has provided the first insight into molecular and structural mechanisms that have enabled octopods to sustain oxygen supply from polar to tropical conditions. Our findings imply modulation of oxygen binding via charge-charge interaction at the protein surface, which stabilize quaternary interactions among functional units to reduce detrimental effects of high pH on venous oxygen release. Of the observed partial haemocyanin sequence, residue 2545 formed a close link between the FU g surface and the active centre, suggesting a role as allosteric binding site. The prevalence of methionine at this site in polar octopods, implies regulation of oxygen affinity via increased sensitivity to allosteric metal binding. High sequence conservation of sites directly involved in oxygen binding indicates that functional modifications of octopod haemocyanin rather occur via more subtle mechanisms, as observed in this study.

Supplement to: Oellermann, Michael; Strugnell, Jan M; Lieb, Bernhard; Mark, Felix Christopher (2015): Positive selection in octopus haemocyanin indicates functional links to temperature adaptation. BMC Evolutionary Biology, 15, 133-150

Identifier
DOI https://doi.org/10.1594/PANGAEA.839802
PID https://hdl.handle.net/10013/epic.44444.d001
Related Identifier https://doi.org/10.1186/s12862-015-0411-4
Related Identifier https://doi.org/10.1023/A:1023335024053
Related Identifier https://doi.org/10.1175/1520-0485(1997)027<1492:TASGCP>2.0.CO
Related Identifier https://doi.org/10.1016/j.dsr2.2006.03.008
Related Identifier https://doi.org/10.1258/002367781780952807
Related Identifier https://doi.org/10.1016/S0990-7440(99)80024-2
Related Identifier https://doi.org/10.1139/z76-099
Related Identifier https://doi.org/10.1016/S0967-0637(00)00050-9
Related Identifier https://doi.org/10.1007/BF00350926
Related Identifier https://doi.org/10.1016/j.aquaculture.2005.03.038
Related Identifier http://bionames.org/references/aab31dc1f1ee9342ee9495d667845a6d
Related Identifier https://doi.org/10.1007/978-94-017-8648-5_18
Related Identifier https://www.researchgate.net/publication/230788716
Related Identifier https://doi.org/10.1007/BF00394369
Related Identifier https://doi.org/10.3989/scimar.2011.75n4811
Related Identifier https://doi.org/10.11233/aquaculturesci1953.52.29
Related Identifier https://doi.org/10.1007/BF00348686
Related Identifier https://doi.org/10.1017/S002531540100443X
Related Identifier https://www.researchgate.net/publication/236533019
Metadata Access https://ws.pangaea.de/oai/provider?verb=GetRecord&metadataPrefix=datacite4&identifier=oai:pangaea.de:doi:10.1594/PANGAEA.839802
Provenance
Creator Oellermann, Michael ORCID logo; Strugnell, Jan M (ORCID: 0000-0003-2994-637X); Lieb, Bernhard; Mark, Felix Christopher ORCID logo
Publisher PANGAEA
Publication Year 2015
Rights Creative Commons Attribution 3.0 Unported; https://creativecommons.org/licenses/by/3.0/
OpenAccess true
Representation
Language English
Resource Type Supplementary Dataset; Dataset
Format text/tab-separated-values
Size 603 data points
Discipline Earth System Research
Spatial Coverage (-124.430W, -70.510S, 169.630E, 79.620N)