Multi-genomic analysis of the Cation Diffusion Facilitator transporters from algae

Abstract

Metal transport processes are relatively poorly understood in algae in comparison to higher plants and other eukaryotes. A screen of genomes from 33 taxonomically diverse algal species was conducted to identify members of the Cation Diffusion Facilitator (CDF) family of metal ion transporter. All algal genomes contained at least one CDF gene with four species having >10 CDF genes (median of 5 genes per genome), further confirming that this is a ubiquitous gene family. Phylogenetic analysis suggested a CDF gene organisation of five groups, which includes Zn-CDF, Fe/Zn-CDF and Mn-CDF groups, consistent with previous phylogenetic analyses, and two functionally undefined groups. One of these undefined groups was algal specific although excluded chlorophyte and rhodophyte sequences. The majority of sequences (22 out of 26 sequences) from this group had a putative ion binding site motif within transmembrane domain 2 and 5 that was distinct from other CDF proteins, such that alanine or serine replaced the conserved histidine residue.The phylogenetic grouping was supported by sequence cluster analysis. Yeast heterologous expression of CDF proteins from Chlamydomonas reinhardtii indicated Zn 2+ and Co 2+ transport function by CrMTP1, and Mn 2+ transport function by CrMTP2, CrMTP3 and CrMTP4, which validated the phylogenetic prediction. However, the Mn-CDF protein CrMTP3 was also able to provide zinc and cobalt tolerance to the Zn-and Co-sensitive zrc1cot1 yeast strain. There is wide diversity of CDF transporters within the algae lineage, and some of these genes may be attractive targets for future applications of metal content engineering in plants or microorganisms. broad taxonomic lineage. Furthermore, a characterisation of additional members of the C. reinhardtii MTP gene family was carried out by using yeast heterologous expression to infer the metal substrates and determine metal tolerance functions. Materials and Methods Bioinformatic analysisThirty three algal species genomes were screened from one Charophyta: Klebsormidium nitens; 13 Chlorophyta: Bathycoccus prasinos RCC1105, Botryococcus braunii,

Lack of a Zn/Co substitution ability in the polar diatom Chaetoceros neogracileRS19

“…In addition to the identified ZIP transporters, we also investigated the proteomes of C. neogracile RS19 generated in the current Zn/Co study for the presence of membrane transporter families implicated in metal homeostasis in algae. These include the CDFs, P1B‐type ATPases, and VIT1 families, all of which include protein members reportedly involved in algal metal transport (Cobbett et al 2003; Hanikenne et al 2005; Blaby‐Haas and Merchant 2012; Ibuot et al 2020). Representative CDF proteins and VIT1 were investigated but were not detected.…”