Bacterial SPOR domains bind peptidoglycan (PG) and target proteins to the cell division site by binding to denuded glycan strands that lack stem peptides [2]. This 70 residue domain is composed of two 35 residue repeats found in proteins involved in sporulation and cell division such as FtsN, DedD, and CwlM. This domain is involved in binding peptidoglycan [1]. Two tandem repeats fold into a pseudo-2-fold symmetric single-domain structure containing numerous contacts between the repeats [1]. FtsN is an essential cell division protein with a simple bitopic topology, a short N-terminal cytoplasmic segment fused to a large carboxy periplasmic domain through a single transmembrane domain. These repeats lay at the periplasmic C-terminus. FtsN localises to the septum ring complex.

1: Solution Structure of the Peptidoglycan Binding Domain of Bacillus subtilis Cell Wall Lytic Enzyme CwlC: Characterization of the Sporulation-Related Repeats by NMR(,). Mishima M, Shida T, Yabuki K, Kato K, Sekiguchi J, Kojima C; Biochemistry 2005;44:10153-10163. PMID:16042392

2: Bacterial SPOR domains are recruited to septal peptidoglycan by binding to glycan strands that lack stem peptides. Yahashiri A, Jorgenson MA, Weiss DS; Proc Natl Acad Sci U S A. 2015;112:11347-11352. PMID:26305949