The unusual metal ion binding ability of histidyl tags and their mutated derivatives

Abstract

Polyhistidine-tags are often used for the affinity purification of polyhistidine-tagged recombinant proteins. These sequences are also found in nature and are often highly conserved across different species. However, their exact role in the biological systems is not clear. The purpose of this work is to shed light on the behavior of poly-His sequences in their interactions with metal ions. This work illustrates the first study of novel poly-(His-Ala) peptides that bind Cu(ii) applying both experimental techniques and extensive computational tools. The studied novel peptides are analogues of the short protected fragment of the pHpG (EDDH9GVG10) peptide, which was found in the venom of Atheris squamigera. Our study presents the properties of metal ion binding-histidine tag complexes and their mutated derivatives. The Cu(ii) binding ability in pHG (Ac-EDDH9G-NH2) is more efficient than in the mutated derivatives, although the number of imidazoles that bind to Cu(ii) ions are similar. Finally, the formation of an α-helical structure is observed in pHG and in one of the mutated derivatives, indicating the importance of the sequence in the poly-(His-Ala) tags.

Histidine tracts in human transcription factors: insight into metal ion coordination ability

“…5 , 6 ). We compared our MB3 and MB6 ligands with two other His-rich peptides, a typical (His) 6 tag (Ac-HHHHHH-NH 2 ) and a snake venom peptide fragment with nine consecutive histidines (Ac-EDDHHHHHHHHH-NH 2 ) [ 1 , 2 , 41 , 42 ]. In the case of zinc complexes, the outcome of these comparisons is easier to explain—both our 18-His and 22-His fragments (MB3 and MB6, respectively) bind Zn 2+ with higher affinity than the His 6 -tag and the 9-His fragment (Figs.…”

Investigation on the metal binding sites of a putative Zn(ii) transporter in opportunistic yeast species Candida albicans

“…These results confirm the previous observation that with the increase of the number of histidines, the coordination becomes more effective. [27][28][29][30] It is important to emphasize that L3 contains both the other two peptides. No direct evidence on the preferred metal binding site of L3 is available, although the higher affinity of L1 with respect to L2 suggests that the distribution of mono-nuclear species where the metal ion is bound to L3 is unbalanced in favour of the Nterminal binding site.…”

“…Both the ligands contain 5 histidines, but the alternate sequence seems to be more effective in binding the Cu(II) ion at physiological pH, in agreement with literature where it is reported that the alternate His-tag -AHAHAHAH-confers more stability to the Cu(II) complexes than the consecutive His-tag with four histidines. 27…”

Metal Complexes of Two Specific Regions of ZnuA, a Periplasmic Zinc(II) Transporter from Escherichia coli

“…This finding is also in good agreement with our previous findings that show that the more histidines are present in the peptide sequence, the more likely it is for amides to participate in Cu(II) binding at a higher pH than usual. 30 , 33 , 34 , 38 …”