Disease relevance of PMEU1

• Expression of pmeu1 in tobacco (Nicotiana tabacum) under the control of the cauliflower mosaic virus 35S promoter caused up to a 4-fold increase in PME specific activity that was correlated with the accumulation of PMEU1 mRNA [1].
• The effects of extended heat stress on polygalacturonase (PG; EC 3.2.1.15) and pectin methylesterase (PME; EC 3.1.1.11) gene expression at mRNA, protein and activity levels in ripening tomato fruits were investigated [2].
• Tomato pectin methylesterase: modeling, fluorescence, and inhibitor interaction studies-comparison with the bacterial (Erwinia chrysanthemi) enzyme [3].

High impact information on PMEU1

• We provide genetic evidence that the production of methanol in tomato fruit is regulated by pectin methylesterase (PME, EC 3.1.1.11), an enzyme that catalyzes demethoxylation of pectins [4].
• Pectin methylesterase regulates methanol and ethanol accumulation in ripening tomato (Lycopersicon esculentum) fruit [4].
• Comparison of the deduced amino acid sequence of pmeu1 with other PME homologs showed that the N-terminal halves are highly variable, and the C-terminal halves are relatively conserved in plant PMEs [1].
• Pectin methylesterase (PME), a ubiquitous enzyme in plants, de-esterifies the methoxylated pectin in the plant cell wall [1].
• Hypocotyls and epicotyls show higher accumulation of pmeu1 transcripts compared with cotyledons. pmeu1 represents a single-copy gene in the tomato genome [1].

Biological context of PMEU1

• Conversely, the narrow and deep cleft of the active site of E. chrysanthemi PME hinders this interaction [3].
• Instead, loop regions forming the walls of the catalytic site are much shorter and form a less deep cleft, as already revealed by the carrot PME crystal structure [3].

Associations of PMEU1 with chemical compounds

• De-esterified citrus pectin was more susceptible to ascorbate-induced scission in vitro than methylesterified pectin, suggesting a possible new significance for pectin methylesterase activity in fruit ripening [5].
• The pH-dependent changes in fluorescence emission intensity observed in tomato PME could arise as the result of protonation of an Asp residue with unusually high pKa, thus supporting the hypothesis that Asp132 acts as acid/base in the catalytic cycle [3].

References