Chemical structure of 1-O-(L-erythro-biopterin-2'-yl)-a-glucose isolated from a cyanobacterium Synechococcus sp. PCC 7942

Abstract

A pteridine glycoside in Synechococcus sp. PCC 7942, the structure of which had been tentatively identified as biopterin-glucoside, was isolated and characterized for its exact chemical structure by 2D-NMR spectroscopy. The determined structure is 1-0-(L-erythro-biopterin-2'-yl)-a-glucose. It is the first report on the occurrence of a biopterin-glucoside having a a-configured sugar directly attached at the pteridine ring. This result also supports that the previously purified UDP-glucose: BH4 glucosyltransferase from Synechococcus sp. PCC 7942, which catalyzes the synthesis of BH4-glucoside from UDP-glucose and BH4, is a a-glucosyltransferase.

Synthesis of biopterin and related pterin glycosides

“…1). For example, 2′‐ O ‐(α‐ D ‐glucopyranosyl)biopterin ( 1b ) and its β‐ D ‐ribofuranosyl analog ( 1c ) were isolated from cyanobacteria (14–18), whereas 2′‐ O ‐(2‐acetamido‐2‐deoxy‐β‐ D ‐glucopyranosyl)biopterin (limipterin) ( 1d ) was obtained from a green sulfur photosynthetic bacterium (19). Similar congeners of other pterins having a hydroxyalkyl side chain at C‐6, such as ciliapterin ( 2a ), neopterin ( 3a ), 6‐hydroxymethylpterin ( 4a ), and 6‐(pentahydroxypentyl)pterin ( 5a ), have also been obtained in certain prokaryotes (20–28).…”

“…(15), Spirulina platensis (16), and Synechococcus sp. (17) since its first discovery in 1958. Although some inhibitory activities against tyrosinase (29) and photostabilization of photosynthetic pigments (17, 30) were reported for 1b , no systematic approach to investigate the physiological functions of pterin glycosides has been made so far.…”

“…(17) since its first discovery in 1958. Although some inhibitory activities against tyrosinase (29) and photostabilization of photosynthetic pigments (17, 30) were reported for 1b , no systematic approach to investigate the physiological functions of pterin glycosides has been made so far. Attempts at preparation of pterin glycosides, however, have been made in recent years in view of structural proof of these reported natural products as well as their biological activities and functions.…”

6‐Pyruvoyltetrahydropterin synthase orthologs of either a single or dual domain structure are responsible for tetrahydrobiopterin synthesis in bacteria

“…In order to explore if bPTPS‐I is responsible for the synthesis of BH4 in vivo as the genuine PTPS homolog, the encoding gene in Synechococcus sp. PCC 7942 which produces BH4‐glucoside [5,11] was disrupted by homologous recombination. The mutant, however, showed normal BH4‐glucoside production and growth.…”

Molecular Cloning of Cyanobacterial Pteridine Glycosyltransferases That Catalyze the Transfer of either Glucose or Xylose to Tetrahydrobiopterin

“…Pteridine glycosides such as biopterin and 6-hydroxymethylpterin glycosides have been found in cyanobacteria and anaerobic photosynthetic bacteria (2,4,5,8,11,13,15,17,21). Although the function of these glycosides remains unknown, they are abundant and ubiquitous in cyanobacteria, implying some essential role (3,6,(16)(17)(18)21).…”