The Structural Determination of Phosphosulfolactate Synthase from Methanococcus jannaschii at 1.7-Å Resolution

Abstract

Members of the enolase mechanistically diverse superfamily catalyze a wide variety of chemical reactions that are related by a common mechanistic feature, the abstraction of a proton adjacent to a carboxylate group. Recent investigations into the function and mechanism of the phosphosulfolactate synthase encoded by the ComA gene in Methanococcus jannaschii have suggested that ComA, which catalyzes the stereospecific Michael addition of sulfite to phosphoenolpyruvate to form phosphosulfolactate, may be a member of the enolase superfamily. The ComA-catalyzed reaction, the first step in the coenzyme M biosynthetic pathway, likely proceeds via a Mg 2؉ ion-stabilized enolate intermediate in a manner similar to that observed for members of the enolase superfamily. ComA, however, has no significant sequence similarity to any known enolase. Here we report the x-ray crystal structure of ComA to 1.7-Å resolution. The overall fold for ComA is an (␣/␤) 8 barrel that assembles with two other ComA molecules to form a trimer in which three active sites are created at the subunit interfaces. From the positions of two ordered sulfate ions in the active site, a model for the binding of phosphoenolpyruvate and sulfite is proposed. Despite its mechanistic similarity to the enolase superfamily, the overall structure and active site architecture of ComA are unlike any member of the enolase superfamily, which suggests that ComA is not a member of the enolase superfamily but instead acquired an enolase-type mechanism through convergent evolution.

Getting a Handle on the Role of Coenzyme M in Alkene Metabolism

“…In addition, radioactive labeling experiments identified cysteine as the source of the thiol group in enzymatic transformation of sulfoacetaldehyde to CoM, the final step of CoM biosynthesis (68). To date, four key enzymes from the methanogenic CoM biosynthetic pathway have been identified and characterized in vitro (25,27,70). For more information on methanogenic coenzyme biosynthesis, including CoM, the reader is referred to two recent and detailed reviews (26,67).…”

Arabidopsis Hsa32, a Novel Heat Shock Protein, Is Essential for Acquired Thermotolerance during Long Recovery after Acclimation

“…PSL synthase is involved in the biosynthesis of PSL, the precursor of coenzyme M required for methane production in the hyperthermophilic euryarchaeon, and possibly sulfolactate, a major component (5% dry weight) of mature spores of Bacillus subtilis (Bonsen et al, 1969;Graham et al, 2002). Sequence comparison showed that, because of the three-dimensional structure of PSL synthase, most amino acid residues proposed to interact with the substrates (Wise et al, 2003) were not conserved in the plant Hsa32 orthologs (Liu et al, 2006b), which suggests that the plant protein does not have PSL synthase activity. As well, plants do not contain the remaining genes required for biosynthesis of coenzyme M (Graham et al, 2002).…”

Biological Roles and Therapeutic Potential of Hydroxy-Carboxylic Acid Receptors

“…Similar to HCA 1 , HCA 2 expression was detected at high levels in white and brown adipose tissue (Soga et al, 2003; Tunaru et al, 2003; Wise et al, 2003; Benyo et al, 2005), as well as in differentiated 3T3-L1 adipocytes upon treatment with rosiglitazone (Jeninga et al, 2009). In contrast to the HCA 1 receptor, HCA 2 is expressed in various immune cells including macrophages, neutrophils, dendritic cells, and epidermal Langerhans cells (Schaub et al, 2001; Benyo et al, 2005, 2006; Maciejewski-Lenoir et al, 2006; Kostylina et al, 2008; Tang et al, 2008; Ahmed et al, 2009a).…”

“…While others have never confirmed this, several studies have independently shown by quantitative PCR that the HCA 1 receptor is predominantly expressed in adipose tissue (Wise et al, 2003; Ge et al, 2008; Jeninga et al, 2009; Liu et al, 2009; Ahmed et al, 2010). By using transgenic reporter mice that express monomeric red fluorescent protein under the transcriptional control of endogenous HCA 1 regulatory elements, it was demonstrated on a cellular level that HCA 1 expression is indeed localized to adipocytes (Ahmed et al, 2010).…”

“…Nicotinic acid was shown to bind with high affinity to human HCA 2 with dissociation constants ( K d ) between 55 and 96 nM (Soga et al, 2003; Tunaru et al, 2003; Wise et al, 2003), and it activated mouse and human HCA 2 in a Ca 2+ reporter assay with EC 50 values of about 3 and 1 μM, respectively (Tunaru et al, 2003). Because endogenous plasma levels of nicotinic acid are too low to activate HCA 2 , it is unlikely that nicotinic functions as a physiological ligand of the HCA 2 receptor (Gille et al, 2008).…”