Chloramphenicol inhibits eukaryotic Ser/Thr phosphatase and infection-specific cell differentiation in the rice blast fungus

Abstract

Chloramphenicol (Cm) is a broad-spectrum classic antibiotic active against prokaryotic organisms. However, Cm has severe side effects in eukaryotes of which the cause remains unknown. The plant pathogenic fungus Magnaporthe oryzae , which causes rice blast, forms an appressorium to infect the host cell via single-cell differentiation. Chloramphenicol specifically inhibits appressorium formation, which indicates that Cm has a novel molecular target (or targets) in the rice blast fungus. Application of the T7 phage display method inferred that MoDullard, a Ser/Thr-protein phosphatase, may be a target of Cm. In animals Dullard functions in cell differentiation and protein synthesis, but in fungi its role is poorly understood. In vivo and in vitro analyses showed that MoDullard is required for appressorium formation, and that Cm can bind to and inhibit MoDullard function. Given that human phosphatase CTDSP1 complemented the MoDullard function during appressorium formation by M. oryzae , CTDSP1 may be a novel molecular target of Cm in eukaryotes.

Selective toxicity of antibacterial agents—still a valid concept or do we miss chances and ignore risks?

“…However, cDNA sequencing showed that only the alleles without the nonsense mutation were being amplified, possibly due to the targeting of nonsense alleles to nonsense-mediated mRNA decay. Chloramphenicol may act through a mechanism other than stop codon read-through [ 275 ] Chloramphenicol n.a In vitro molecular. Read-through level of cspC UGA in E. coli Chloramphenicol increased read-through [ 276 ] Oxazolidinones Linezolid n.a In vitro molecular , lacZ ± UAG or UGA Induction of read-through [ 273 ] Linezolid, Rχ-01 n.a In vitro molecular , lacZ ± UAG or UGA Linezolid induced read-through 5-times less efficient than the investigational oxazolidin Rχ-01 [ 277 ] Tetracyclines Tetracycline n.a In vitro molecular.…”

“…Read-through level of cspC UGA in E. coli Chloramphenicol increased read-through [ 276 ] Oxazolidinones Linezolid n.a In vitro molecular , lacZ ± UAG or UGA Induction of read-through [ 273 ] Linezolid, Rχ-01 n.a In vitro molecular , lacZ ± UAG or UGA Linezolid induced read-through 5-times less efficient than the investigational oxazolidin Rχ-01 [ 277 ] Tetracyclines Tetracycline n.a In vitro molecular. Read-through level of cspC UGA in E. coli Tetracycline increased read-through [ 275 ] Doxycycline Breast cancer In vitro cellular, murine breast cancer EMT6 cells. The genetic code of the amino acid selenocysteine is UGA Most selenoproteins are oxidoreductases involved in housekeeping processes and stressresponse.…”

“…The impact of chloramphenicol on gene expression in eukaryotes is possibly due to alternative mechanisms or downstream effects to inhibition of mitochondrial translation resulting in decreases in cell surface transferrin expression, de novo ferritin synthesis, thus affecting iron dependent respiratory chain activity resulting in an reduced ATP synthesis and eventually in reduced tumor cell growth (Table S1). It has been shown recently that chloramphenicol inhibited appressorium formation in Magnaporthe oryzae because of an inhibition of MoDullard, a serine/threonine phosphatase [ 275 ]. Alignment and comparison of amino acid sequences of fungal and human origin revealed that five MoDullard orthologs could be identified from the human genome but only caboxy-terminal domain RNA polymerase II polypeptide A small phosphatase 1 (CTDSP1) complemented the MoDullard function and could be inhibited by chloramphenicol.…”

“…Small serine phosphatases can exhibit multiple functions in a variety of cellular and biological processes. Human CTDSP1 interacts with a variety of proteins like cell division cycle associated protein 3, myelin basic protein, RE1-silencing transcription factor, some of which are involved in cell differentiation [ 275 ]. If CTDSP1 may represent a novel target for chloramphenicol in humans has to be verified or falsified.…”

Methods for Identification of Substrates/Inhibitors of FCP/SCP Type Protein Ser/Thr Phosphatases

“…These data suggest that Scp1 may represent a potential drug target and Scp1-specific inhibitors may represent valuable therapeutics for preventing the spreading of particular tumors. To date, some studies have reported specific inhibitors for FCP/SCP-type PSPs, including for Scp1 [30,31]. It is reported that rabeprazole, which is a drug for gastroesophageal reflux disease, can function as a specific inhibitor for Scp phosphatases including Scp1, but it did not show the inhibitory activity against other FCP/SCP type phosphatase, Fcp1 and Dullard, or bacteriophage λ Ser/Thr phosphatases [30,32].…”