Snow, Joe T., Baylay, Alison, Polyviou, Despo, Skipp, Paul, Moore, Mark, Achterberg, Eric P. and Bibby, Thomas S. (2016) Exploring the metalloproteome and metallome of Trichodesmium in culture and the (sub)-tropical Atlantic. [Talk] In: Challenger Society Annual Conference 2016. , 05.-08.09.2016, Liverpool, UK .

Abstract

Trichodesmium sp. is a globally important marine cyanobacterium that accounts for a significant proportion of the annual ‘new’ nitrogen introduced into the global ocean. These non-heterocystous diazotrophs employ a unique strategy of near concurrent nitrogen fixation and oxygenic photosynthesis without complete cellular segregation. Trichodesmium is subsequently burdened with a particularly high iron requirement due to the iron rich proteins involved in both process. With an estimated 1 in 3 proteins containing a metal co-factor the wider study of transition metals in the marine environment is increasingly being pursued. Unlike iron, comparatively little is understood about the broader micronutrient and trace-metal requirements of Trichodesmium in either culture or the environment. Here we take a multi-faceted approach towards understanding Trichodesmium’s iron, phosphorus and broader trace-metal requirements by pairing label-free quantitative proteomics data (UPLC-MSE) with both shotgun metagenomic (Illumina) and metallomic (ICP-MS) approaches. Environmental Trichodesmium populations were isolated from a north-south meridional transect covering an antithetical gradient of dissolved iron and dissolved inorganic phosphorus. Highlighting the abundance of both phosphorus and iron stress biomarker proteins we compare the proteomic profile of these environmental isolates with that of high and low iron phenotypes previously observed in culture. Further, an exploration of Trichodesmium’s proteomic and metallomic composition reveals the importance of other less well studied trace-metals, their roles in carbon and nitrogen fixation, nutrient acquisition and the avoidance of oxygenic stress alongside their potentially limiting environmental availability.

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