Binds 1 zinc ion per subunit. Expression is maximal during the early to mid-log stage of growth and decreases after. Does not respond to heat shock up to 43 degrees Celsius. Part of the lemA-htpX operon. No effect on extracellular glucosyltransferase activity, nor on growth characteristics. Deletion does however alter cell surface appearance, making cells rougher at 41.5 degrees Celsius. They are also slightly less adhesive on hydroxyapatite. Belongs to the peptidase M48B family.