Lentimonas catalyze the degradation of complex sulfated fucans in the ocean

ABSTRACT: Brown algae synthesize various polysaccharides that are ultimately catabolized by marine heterotrophic bacteria. Complex cell wall polysaccharides such as sulfated fucans are considered recalcitrant to microbial degradation and their pathways remain elusive. The branched structure of fucans sterically constraints enzyme-substrate interaction and also, fucan structure varies depending on algae and season challenging adaptation of microbial pathways. Here we show how Lentimonas specialized to overcome the complexity and diversity of sulfated fucans. The strain acquired a 0.9 mbp plasmid with over 200 glycoside hydrolases and sulfatases for the degradation of at least six different sulfated fucans. Per fucan, 100 enzymes are induced and we identified three structural types of fucans with similar pathways depending on their galactose, acetate and sulfate content. The highly decorated structure sulfated fucans expands the copy number and diversity of few key enzyme families, namely GH29, GH95, GH141 and sulfatases S1_15, S1_16 and S1_17. Those enzymes are co-regulated in large operons to step-wise degrade sulfated fucans. Fucose metabolism places additional burden as the conversion of toxic intermediates into lactate and propanediol occurs in a proteome-costly bacterial microcompartment. Through analyzing available genomes and metagenomes, we emphasize that Verrucomicrobia are abundant, yet specialized degraders of complex polysaccharides.

INSTRUMENT(S): LTQ Orbitrap

ORGANISM(S): Lentimonas

SUBMITTER: Marie-Katherin Zühlke  

LAB HEAD: Marie-Katherin Zühlke

PROVIDER: PXD015328 | Pride | 2021-01-20

REPOSITORIES: Pride