Investigating the metal binding properties of MEMO1

MEMO1 is an evolutionarily conserved protein involved in various biological processes, notably playing a crucial role in breast cancer cell metastasis, as demonstrated in both in vivo and in vitro studies (MacDonald et al, 2014). Recent findings suggest that MEMO1 binds to both iron and copper in vitro (Dolgova et al, 2024). However, during MEMO1 purification, the affinity chromatography column turned pink-a phenomenon not observed with the C244S mutant, which is unable to bind metal. It was hypothesized that this colour change was due to  MEMO1 forming a complex with either cobalt or manganese, the two biologically significant metals that commonly form pink-coloured complexes. To test this hypothesis, both MEMO1 and the C244S variant were purified using affinity chromatography, and the protein-metal complex containing fractions were analyzed using inductively coupled plasma mass spectrometry (ICP-MS). With the purified protein,  metal binding assays using  UV-Vis spectroscopy were also conducted. However, no significant shifts in the absorbance peaks were detected, indicating that MEMO1 may not bind manganese or cobalt as initially hypothesized.