TY  - JOUR
A1  - Patterson, Jenelle A.
A1  - He, Hai
A1  - Folz, Jacob S.
A1  - Li, Qiang
A1  - Wilson, Mark A.
A1  - Fiehn, Oliver
A1  - Bruner, Steven D.
A1  - Bar-Even, Arren
A1  - Hanson, Andrew D.
T1  - Thioproline formation as a driver of formaldehyde toxicity in Escherichia coli
JF  - Biochemical Journal
N2  - Formaldehyde (HCHO) is a reactive carbonyl compound that formylates and cross-links proteins, DNA, and small molecules. It is of specific concern as a toxic intermediate in the design of engineered pathways involving methanol oxidation or formate reduction. The interest in engineering these pathways is not, however, matched by engineering-relevant information on precisely why HCHO is toxic or on what damage-control mechanisms cells deploy to manage HCHO toxicity. The only well-defined mechanism for managing HCHO toxicity is formaldehyde dehydrogenase-mediated oxidation to formate, which is counterproductive if HCHO is a desired pathway intermediate. We therefore sought alternative HCHO damage-control mechanisms via comparative genomic analysis. This analysis associated homologs of the Escherichia coli pepP gene with HCHO-related one-carbon metabolism. Furthermore, deleting pepP increased the sensitivity of E. coli to supplied HCHO but not other carbonyl compounds. PepP is a proline aminopeptidase that cleaves peptides of the general formula X-Pro-Y, yielding X + Pro-Y. HCHO is known to react spontaneously with cysteine to form the close proline analog thioproline (thiazolidine-4-carboxylate), which is incorporated into proteins and hence into proteolytic peptides. We therefore hypothesized that certain thioproline-containing peptides are toxic and that PepP cleaves these aberrant peptides. Supporting this hypothesis, PepP cleaved the model peptide Ala-thioproline-Ala as efficiently as Ala-Pro-Ala in vitro and in vivo, and deleting pepP increased sensitivity to supplied thioproline. Our data thus (i) provide biochemical genetic evidence that thioproline formation contributes substantially to HCHO toxicity and (ii) make PepP a candidate damage-control enzyme for engineered pathways having HCHO as an intermediate.
KW  - formaldehyde
KW  - thiazolidine-4-carboxylic acid
KW  - thioproline
KW  - Xaa-Pro aminopeptidase
Y1  - 2020
U6  - https://doi.org/10.1042/BCJ20200198
SN  - 1470-8728
SN  - 0006-2936
VL  - 477
IS  - 9
SP  - 1745
EP  - 1757
PB  - Portland Press
CY  - London
ER  -