Part:BBa_K4990007
HlpA
Usage in short
You can use it to target coloretal cancer!
Sequence and Features
- 10COMPATIBLE WITH RFC[10]
- 12COMPATIBLE WITH RFC[12]
- 21COMPATIBLE WITH RFC[21]
- 23COMPATIBLE WITH RFC[23]
- 25INCOMPATIBLE WITH RFC[25]Illegal NgoMIV site found at 231
- 1000COMPATIBLE WITH RFC[1000]
What is it?
Here is the structure of Dual-Edged Harpoon.The name,"Harpoon",is the nickname we call it.Of course, you can call it more formally as "Dual-targeted Cytotoxic peptide".
What you need to know!
2006年Tjalsma通过Highly accurate tandem MS方法，找到了一种蛋白Histone-like protein A(HlpA),发现它联系Streptococcus bovis和结直肠癌的桥梁，并推测S.bovis正是通过HlpA与结直肠癌细胞表面的heparan sulfate-proteoglycans(HSPG)结合，介导的S.bovis定植于结直肠癌[1]。
2009年Boleij证明了Streptococcus gallolyticus通过HlpA于结直肠癌细胞表面的HSPG结合[2]。
2016年O'Neil得到了Hlp的晶体结构，指示Hlp为类似蟹钳的结构，钳子部分的碱性氨基酸可以与DNA结合，同时也可以与肝素结合[3]。
2018年Chun Loong Ho利用HlpA与HSPG的结合，构建了一种可以靶向结直肠癌的工程大肠杆菌，拉开了HlpA靶向系统的序幕[4]。
2022年iGEM22_LZU-CHINA 团队，通过合成生物学构建了靶向结直肠癌的大肠杆菌，方法为HlpA靶向肿瘤细胞表面的HSPG[5]。
2023年Tang构建了利用HlpA靶向，Azurin杀伤的工程益生菌，并在结直肠癌小鼠中展现出不错的疗效[6]。
Therefore, HlpA possesses dual capabilities: 1. Targeting colorectal cancer and 2. Non-specifically binding to DNA chains.
What is it?
Here is the structure of HlpA monomer and homodimer.
Two helical segments from each monomeric subunit constitute an α-helical ‘body’ with two protruding β-ribbon ‘arms’ , which extend to bind the DNA helix. These DNA-binding β-ribbons are largely disordered in the absence of DNA.
What can it do?
HlpA单体被用于设计融合蛋白，它可以与结直肠癌细胞表面的HSPG进行结合。因此，如果你想用蛋白靶向结直肠癌细胞，你就可以设计一个融合蛋白，将HlpA挂在融合蛋白的一端。如果你想让细胞靶向结直肠癌细胞，则可以为你的底盘细胞量身定制一种包含HlpA的膜蛋白，通过表面展示技术将HlpA表达在地盘细胞表面，它就可以用于靶向结直肠癌细胞[4-6]。
除此之外，HlpA类似于大肠杆菌的HU蛋白。大肠杆菌HU异源二聚体与双链DNA非特异性结合，与结构扭曲的DNA具有更高的亲和力，从而导致显著的DNA弯曲、DNA压实和负超螺旋的形成。HlpA与DNA的结合具有非特异性的，并且对富含AT的DNA具有偏好性[3]。
最后，不得不提到的是，这些HlpA单体可以自组装为同源二聚体，它们之间的结合具有巨大的亲和力。因此，在我们的双靶向肽相关实验中，观察到了显著的二聚化现象。
How does it work?
Examination of the DNA-binding region of Hlp revealed that this area is primarily composed of positively charged residues that form a pocket to accommodate DNA binding. The specific residues that comprise the DNA-binding pocket are depicted in Figure below. It should be noted that the side-chain electron density for Arg56, Lys60, Lys71 and Lys73 of subunit A and Arg54, Lys76 and Lys81 of subunit B was partially disordered and could not be traced in the electrondensity maps. Therefore, the side chains were modeled in idealized rotamer positions for the electrostatic surface calculations.[3]
Referrence
[1]Tjalsma H, Schöller‐Guinard M, Lasonder E, et al. Profiling the humoral immune response in colon cancer patients: diagnostic antigens from Streptococcus bovis[J]. International journal of cancer, 2006, 119(9): 2127-2135.
[2]Boleij A, Schaeps R M J, de Kleijn S, et al. Surface-exposed histone-like protein a modulates adherence of Streptococcus gallolyticus to colon adenocarcinoma cells[J]. Infection and immunity, 2009, 77(12): 5519-5527.
[3]O'Neil P, Lovell S, Mehzabeen N, et al. Crystal structure of histone-like protein from Streptococcus mutans refined to 1.9 Å resolution[J]. Acta Crystallographica Section F: Structural Biology Communications, 2016, 72(4): 257-262.
[4]Ho C L, Tan H Q, Chua K J, et al. Engineered commensal microbes for diet-mediated colorectal-cancer chemoprevention[J]. Nature biomedical engineering, 2018, 2(1): 27-37.
[5]https://2022.igem.wiki/lzu-china/
[6]Tang, H., Zhou, T., Jin, W., Zong, S., Mamtimin, T., Salama, E. S., ... & Li, X. (2023). Tumor-targeting engineered probiotic Escherichia coli Nissle 1917 inhibits colorectal tumorigenesis and modulates gut microbiota homeostasis in mice. Life Sciences, 324, 121709.
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