Glucuronan lyases from family PL7 use a Tyr/Tyr syn β-elimination catalytic mechanism for glucuronan breakdown

TpPL7A and TpPL7B, members of CAZy family PL7, act as beta-glucuronan lyases. TpPL7A diverges by lacking the catalytic histidine, identified as the Bronsted base in PL7 alginate lyases. Our research, including TpPL7A's crystal structure, and mutagenesis studies, reveals a shared syn-beta-elimination mechanism with a single tyrosine serving as both base and acid catalyst. This mechanism may extend to subfamily PL7_4 glucuronan lyases.

Automated summary

The research reveals that TpPL7A lacks the catalytic histidine found in PL7 alginate lyases but still utilizes a tyrosine to achieve a shared syn-beta-elimination mechanism. This mechanism may also be applicable to subfamily PL7_4 glucuronan lyases.