In Vivo Characterization of Dimethylsulfoniopropionate Lyase in the Fungus Fusarium lateritium

Abstract

A fungus, Fusarium lateritium, with dimethylsulfoniopropionate (DMSP) lyase activity was isolated from both seawater and a salt marsh due to its ability to grow on DMSP (with the evolution of dimethyl sulfide) as the sole source of carbon. This is the first reported case of DMSP lyase activity in a fungus. Several other common fungal genera tested did not have DMSP lyase activity. DMSP was taken up more rapidly by F. lateritium than it was utilized, leading to its intracellular accumulation. Inhibitor studies with nystatin and cyanide indicated that DMSP uptake was an energy-dependent process. The lyase was inducible by its substrate, DMSP (Km , 1.2 mM), and by the substrate analogs choline and glycine betaine. During induction, DMSP lyase activity increased with time and then dropped rapidly. This loss of activity could be prevented by spiking the culture with fresh DMSP or choline. The V max for DMSP lyase was 34.7 mU · mg of protein−1. The inhibitory effects of nystatin, andp-chloromercuriphenylsulfonate on DMSP lyase activity suggested that the enzyme is cytosolic. Because plants likeSpartina (a marsh grass) and marine algae contain high concentrations of DMSP, we speculate that DMSP-utilizing fungi may be involved in their decay.

The dddP gene, encoding a novel enzyme that converts dimethylsulfoniopropionate into dimethyl sulfide, is widespread in ocean metagenomes and marine bacteria and also occurs in some Ascomycete fungi

“…It was striking to find dddP‐ like genes in Ascomycete fungi. Some Ddd + Ascomycetes, including Fusarium species, had been isolated from mud in stands of the DMSP‐producing Spartina (Bacic and Yoch, 1998; Bacic et al ., 1998), and it seems likely that these fungi, too, may contain dddP. Several observations suggest that the presence of dddP in these eukaryotes is due to inter‐domain HGT.…”

TROPHIC INTERACTIONS IN THE SEA: AN ECOLOGICAL ROLE FOR CLIMATE RELEVANT VOLATILES?1

“…Several marine bacteria (e.g. de Souza and Yoch 1995), a heterotrophic dinoflagellate (Kadota and Ishida 1968), the marine fungus Fusarium lateritium (Bacic and Yoch 1998), and various marine micro‐ and macroalgae (e.g. Stefels and van Boekel 1993, Steinke et al 1996) produce this enzyme.…”

High Soil Sulfur Promotes Invasion of Exotic Spartina alterniflora into Native Phragmites australis Marsh

“…Fungi (especially Ascomycetes) are the predominant decomposers of S. alterniflora and are involved in the DMS release . The high release rates of DMS in S. alterniflora marshes have a temporal peak coinciding with the peak shoot death; a strong correlation exists between a fungal decomposer's ability and the host plant's production of DMSP as a secondary product . rRNA from SRBs accounts for up to 43% of the bacterial rRNA in marsh sediments colonized by S. alterniflora , with the highest percentages of bacteria physically associated with root surface .…”