Structural and Biochemical Characterization of a Novel Aminopeptidase from Human Intestine

Abstract

Background: A protein product of the NAALADL1 gene is a homolog of glutamate carboxypeptidase II, a metallopeptidase studied as a promising theranostic cancer agent. Results: We solved the x-ray structure and analyzed the substrate specificity of the NAALADL1 gene product. Conclusion:We demonstrated that the protein represents a novel human ileal aminopeptidase. Significance: This study describes a novel enzyme involved in protein/peptide digestion in the small intestine and clarifies controversial previous reports.

Structural modelling of the lumenal domain of human GPAA1, the metallo-peptide synthetase subunit of the transamidase complex, reveals zinc-binding mode and two flaps surrounding the active site

“…For each leave of the phylogenetic tree, we list (i) a color code, (ii) the taxonomic abbreviation, (iii) the accession number from the protein data bank RCSB or UniProt, (iv) the sequence segment from the original sequence used for the alignment behind the tree, (v) the sequence length of the sequence segment and (vi) the molecular function code (AM aminopeptidase, CP carboxypeptidase, CT cyclotransferase, CTI cyclotransferase type I, CTII cyclotransferase type II). The sequence groups presented in the phylogenetic tree are (i) known two zinc-binding 3D structures 3fec [61], 1zbl [59], 4twe [64], 5ib9, 6hc6, 3iib, 1tkj, 1amp [28], 5gne [65], and 6esl [66] color-coded red; (ii) known single zinc-binding 3D structures 49fu [30], 4mhn, 4fai [30], 3pb4 [62], 2afo [60], 3si1 [63], 6qql, 3tc8, and 4fuu color-coded green as well as (iii) six sequences from the GPAA1 family color-coded blue. We show also the position of 3gux in the tree although it is not known how many zinc ions it does bind in the catalytic cleft (we predict one) as it was part of the alignment in Figure 1 of reference [23].…”

The calcium‐binding site of human glutamate carboxypeptidase II is critical for dimerization, thermal stability, and enzymatic activity

“…[21][22][23][24][25][26] The M28B subfamily, to which human GCPII belongs, includes peptidases homologous to GCPII as well as the transferrin receptor (TfR), a protein devoid of enzymatic activity. X-ray structures for three GCPII homologs from the M28B subfamily are available in the Protein Data Bank: glutamate carboxypeptidase III (GCP3), 27 N-acetylated alpha-linked acidic dipeptidase-like protein (NAALADaseL), 28 and TfR. 29,30 The partial sequence and structural alignments of these homologs and SGAP 31 are shown in Figure 6.…”

68Ga-PSMA-HBED-CC PET for Differential Diagnosis of Suggestive Lung Lesions in Patients with Prostate Cancer

“…This result raises the question whether binding to a substance other than PSMA might be a possible contributing factor. Natural candidate proteins would include PSMA homologs, such as glutamate carboxypeptidase III (21,22) or N-acetylated a-linked acidic dipeptidaselike protein (23). Further insight could be gained by performing tracer uptake assays on tumor cell lines, therefore excluding the effect of tracer binding to neovasculature.…”