Table 1. Summary of endonuclease activity on T4 DNA and protein expression levels of WT and mutant forms of Eco94GmrSD.

Enzyme	Endonuclease activity	Protein expression level
WT	+++ Active (100%)	++
C-terminus mutants (1 to 6)
1) D507A	Inactive (binding+/−)	++
2) H508A	Inactive (binding+)	++
3) C517A	+ Partially active	++
4) N522A	Inactive (binding+/−)	+
5) N528A	+ Partially active	++
6) N535A	+ Partially active	++
Possible Eco94GmrSD endonuclease catalytic site: D507-H508-N522. Binding+, bound/shifted complexes detected at all four protein concentrations tested; binding+/−, bound/shifted complexes were detected only at high enzyme concentrations.