Methods and compositions related to peptides and proteins with c-terminal elements
Disclosed are compositions and methods useful for targeting and internalizing molecules into cells of interest and for penetration by molecules of tissues of interest. The compositions and methods are based on peptide sequences that are selectively internalized by a cell, penetrate tissue, or both. The disclosed internalization and tissue penetration is useful for delivering therapeutic and detectable agents to cells and tissues of interest.
1 . A method of forming an activatable CendR element, the method comprising (a) selecting an amino acid sequence for internalization into a cell, tissue penetration, or both, wherein the amino acid sequence comprises a CendR element comprising a terminal carboxyl group, (b) causing a blocking group to be covalently coupled to the terminal carboxyl group of the CendR element, wherein a bond coupling the blocking group and the CendR element is cleavable, wherein the blocking group covalently coupled to the CendR element reduces or prevents internalization into a cell, tissue penetration, or both, wherein the activatable CendR element comprises the selected amino acid sequence and the blocking group, wherein cleavage of the activatable CendR element exposes the terminal carboxyl group of the CendR element, wherein the amino acid sequence is circular, and wherein the CendR element comprises the sequence KLAK (amino acids 11-14 of SEQ ID NO:5), KPAR (amino acids 4-7 of SEQ ID NO: 114), KPER (amino acids 4-7 of SEQ ID NO:90), KPLR (amino acids 4-7 of SEQ ID NO: 63), KPRR (amino acids 5-8 of SEQ ID NO: 126), KQAR (amino acids 4-7 of SEQ ID NO: 64), KRDR (amino acids 3-6 of SEQ ID NO:89), KRER (amino acids 4-7 of SEQ ID NO:91), KTAR (amino acids 3-6 of SEQ ID NO:56), RGDK (amino acids 2-5 of SEQ ID NO:4), RPAK (amino acids 4-7 of SEQ ID NO: 112), or RTPK (amino acids 4-7 of SEQ ID NO:84).
2 . The method of claim 1 , wherein the activatable CendR element is a protease-activatable CendR element.
3 . The method of claim 1 , wherein the amino acid sequence is selected for internalization into a cell.
4 . The method of claim 1 , wherein the amino acid sequence is selected for tissue penetration.
5 . The method of claim 1 , wherein the amino acid sequence is selected for internalization into a cell and tissue penetration.
6 . The method of claim 1 , wherein the blocking group covalently coupled to the CendR element reduces or prevents internalization into a cell.
7 . The method of claim 1 , wherein the blocking group covalently coupled to the CendR element reduces or prevents tissue penetration.
8 . The method of claim 1 , wherein the blocking group covalently coupled to the CendR element reduces or prevents internalization into a cell and tissue penetration.
9 . An activatable CendR element made by a method comprising (a) selecting an amino acid sequence for internalization into a cell, tissue penetration, or both, wherein the amino acid sequence comprises a CendR element comprising a terminal carboxyl group, (b) causing a blocking group to be covalently coupled to the to the terminal carboxyl group of the CendR element, wherein a bond coupling the blocking group and the CendR element is cleavable, wherein the blocking group covalently coupled to the CendR element reduces or prevents internalization into a cell, tissue penetration, or both, wherein the activatable CendR element comprises the selected amino acid sequence and the blocking group, wherein cleavage of the activatable CendR element exposes the terminal carboxyl group of the CendR element, and wherein the amino acid sequence is circular, and wherein the CendR element comprises the sequence KLAK (amino acids 11-14 of SEQ ID NO:5), KPAR (amino acids 4-7 of SEQ ID NO: 114), KPER (amino acids 4-7 of SEQ ID NO:90), KPLR (amino acids 4-7 of SEQ ID NO: 63), KPRR (amino acids 5-8 of SEQ ID NO: 126), KQAR (amino acids 4-7 of SEQ ID NO: 64), KRDR (amino acids 3-6 of SEQ ID NO:89), KRER (amino acids 4-7 of SEQ ID NO:91), KTAR (amino acids 3-6 of SEQ ID NO:56), RGDK (amino acids 2-5 of SEQ ID NO:4), RPAK (amino acids 4-7 of SEQ ID NO:112), or RTPK (amino acids 4-7 of SEQ ID NO:84).
10 . The CendR element of claim 9 , wherein the activatable CendR element is a protease-activatable CendR element.
11 . The CendR element of claim 9 , wherein the method further comprises, prior to step (b), selecting the bond coupling the blocking group and the terminal carboxyl group to be cleavable by a protease present in proximity to the cell.
12 . The CendR element of claim 9 , wherein the blocking group is coupled to the C-terminal amino acid of the CendR element.
13 . The CendR element of claim 9 , wherein the blocking group is coupled to an amino acid of the CendR element other than the C-terminal amino acid of the CendR element.
14 . The CendR element of claim 9 , wherein a cargo composition is covalently coupled or non-covalently associated with a protein or peptide comprising the selected amino acid sequence, wherein the cargo composition is coupled or associated with the protein or peptide on the N terminal side of the CendR element.
15 . The CendR element of claim 9 , wherein the amino acid sequence is selected for internalization into a cell.
16 . The CendR element of claim 9 , wherein the amino acid sequence is selected for tissue penetration.
17 . The CendR element of claim 9 , wherein the amino acid sequence is selected for internalization into a cell and tissue penetration.
18 . The CendR element of claim 9 , wherein the blocking group covalently coupled to the CendR element reduces or prevents internalization into a cell.
19 . The CendR element of claim 9 , wherein the blocking group covalently coupled to the CendR element reduces or prevents tissue penetration.
20 . The CendR element of claim 9 , wherein the blocking group covalently coupled to the CendR element reduces or prevents internalization into a cell and tissue penetration.