ABSTRACT
A new intracellular mRNA imaging probe has been developed that incorporates thiol-terminated hairpin oligonucleotides covalently bound to the surface of citrate-capped gold nanoparticles. The hairpin DNA-coated gold nanoparticles (hAuNPs) positively identifies tyrosinase mRNA in cultured melanoma cells.
Subject(s)
Gene Expression Regulation, Neoplastic , Inverted Repeat Sequences , Melanoma/diagnosis , Monophenol Monooxygenase/genetics , Nanoparticles , Oligonucleotides , RNA, Messenger/analysis , Cell Line, Tumor , Gold/chemistry , Humans , Melanoma/genetics , Microscopy, Confocal/methods , Microscopy, Fluorescence/methods , Nanoparticles/chemistry , Oligonucleotides/chemistry , RNA, Messenger/genetics , Sulfhydryl Compounds/chemistryABSTRACT
Enzymatic haem catabolism by haem oxygenases is conserved from bacteria to humans and proceeds through a common mechanism leading to the formation of iron, carbon monoxide and biliverdin. The first members of a novel class of haem oxygenases were recently identified in Staphylococcus aureus (IsdG and IsdI) and were termed the IsdG-family of haem oxygenases. Enzymes of the IsdG-family form tertiary structures distinct from those of the canonical haem oxygenase family, suggesting that IsdG-family members degrade haem via a unique reaction mechanism. Herein we report that the IsdG-family of haem oxygenases degrade haem to the oxo-bilirubin chromophore staphylobilin. We also present the crystal structure of haem-bound IsdI in which haem ruffling and constrained binding of oxygen is consistent with cleavage of the porphyrin ring at the beta- or delta-meso carbons. Combined, these data establish that the IsdG-family of haem oxygenases degrades haem to a novel chromophore distinct from biliverdin.
