We believe that bacterial outer surface bears a unexplored plethora of sugar binding proteins which helps in bacterial cell to cell communications. Do lectins play an important role in bio-films?
As you say, there are many different lectins on the outer surface of bacteria. While the interaction of these lectins is not 100% specific, it is much more specific than something like the extracellular matrix. This means that depending on the environment and the available binding sites, lectins can play a role in adhesion of bacterial cells to surfaces and to one another, thereby promoting biofilm formation.
There are many aspects of the cell surface that are largely under explored and it is likely that, as you suggest, the sugar binding or lectin binding proteins are but one example. In the medical arena, there is a fairly substantive history of studying lectin binding proteins and how the mediate ‘lock and key’ style binding to host receptors or to surface markers on other bacteria. For example, co-aggregation studies have typically used sugars to investigate cell-cell interactions mediated by these sorts of biopolymers.
It is an interesting second question, probably distinct from the question around their role in biofilm formation, where you ponder whether such proteins play a role in cell-cell communication. While it seems unlikely they play a role in small molecule mediated signalling (communication) it is possible that they non-the-less play some role in recognition of other cells, either conspecific or not, and in that way trigger changes in gene expression or response. For example, the C-signal of Myxobacteria is a protein that is involved in signalling by binding the poles of two Mycobacteria cells. Having not followed this field for sometime, it is not clear if this has a lectin like component, but presumably there is a receptor required, so who knows.
- Answered in consultation with A/Prof. Scott Rice (SCELSE), whose research is centred on how and why bacteria form matrix encased biofilms.