Inhibitory mechanism of novel inhibitors of UDP-N-acetylglucosamine enolpyruvyl transferase from Haemophilus influenzae.
Bacterial UDP-N-acetylglucosamine enolpyruvyl transferase (MurA) catalyzes the transfer of enolpyruvate from phosphoenolphyruvate (PEP) to uridine diphospho-N-acetylglucosamine (UNAG), which is the first step of bacterial cell wall synthesis. We identified thimerosal, thiram, and ebselen as effective inhibitors of Heamophilus influenzae MurA by screening a chemical library that consisted of a wide range of bioactive compounds. When MurA was preincubated with these inhibitors, their 50% inhibitory concentrations (IC50s) were found to range from 0.1 to 0.7 microM. In particular, thimerosal suppressed the growth of several different Gram-negative bacteria such as Escherichia coli, Pseudomonas aeruginosa, Salmonella typhimurium at a concentration range of 1-2 microg/ml. These inhibitors covalently modified the cysteine residue near the active site of MurA. This modification changed the open conformation of MurA to a more closed configuration, which may have prevented the necessary conformational change from occurring during the enzyme reaction.
Jin
Bong-Suk
BS
Department of Chemistry, Kookmin University, 861-1 Jeongneung, Seongbuk, Seoul, 136-702, Korea.
Han
Seong-Gu
SG
Lee
Won-Kyu
WK
Ryoo
Sung Weon
SW
Lee
Sang Jae
SJ
Suh
Se-Won
SW
Yu
Yeon Gyu
YG
D019883:Alkyl and Aryl Transferases / Q000037:antagonists & inhibitors* / Q000737:chemistry; D000975:Antioxidants / Q000494:pharmacology; D001393:Azoles / Q000494:pharmacology; D020134:Catalytic Domain / Q000187:drug effects; D002473:Cell Wall / Q000187:drug effects / Q000201:enzymology; D003545:Cysteine / Q000737:chemistry; D004926:Escherichia coli / Q000187:drug effects / Q000254:growth & development; D005659:Fungicides, Industrial / Q000494:pharmacology; D016905:Gram-Negative Bacterial Infections / Q000378:metabolism / Q000382:microbiology; D006193:Haemophilus influenzae / Q000187:drug effects / Q000201:enzymology*; D006801:Humans; D054833:Isoindoles; D016566:Organoselenium Compounds / Q000494:pharmacology; D011310:Preservatives, Pharmaceutical / Q000494:pharmacology; D011487:Protein Conformation / Q000187:drug effects; D011550:Pseudomonas aeruginosa / Q000187:drug effects / Q000254:growth & development; D012486:Salmonella typhimurium / Q000187:drug effects / Q000254:growth & development; D013849:Thimerosal / Q000494:pharmacology; D013893:Thiram / Q000494:pharmacology
D000975:Antioxidants; D001393:Azoles; D005659:Fungicides, Industrial; D054833:Isoindoles; D016566:Organoselenium Compounds; D011310:Preservatives, Pharmaceutical; D013893:Thiram; D013849:Thimerosal; C042986:ebselen; D019883:Alkyl and Aryl Transferases; C022566:UDP-N-acetylglucosamine 1-carboxyvinyltransferase; D003545:Cysteine