RECOMBINANT LECTIN AND USES THEREOF
Disclosed herein are a recombinant Streptomyces S27S5 hemagglutinin (SHA), and homologues thereof, and a fusion protein of a fluorescent protein (such as GFP and mCherry1) and SHA or a homologue thereof, which specifically bind to carbohydrates, including oligomeric sugars that terminate in L-rhamnose or D-galactose. The SHA, SHA homologues, and fusion proteins can be used to detect a variety of microorganisms or cancer or tumor antigens.
1 . A recombinant Streptomyces S27S5 hemagglutinin (SHA) protein having an amino acid sequence represented by SEQ ID NO: 25 or a homologue thereof having an amino acid sequence at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, at least 98%, or at least 99% identical to that of SEQ ID NO: 25, wherein the SHA protein or a homologue thereof specifically binds to L-rhamnose or D-galactose.
2 . The recombinant SHA protein or a homologue thereof of claim 1 , wherein the recombinant SHA protein or a homologue thereof specifically binds to a carbohydrate that contains or terminates in a monosaccharide or an oligosaccharide selected from the group consisting of β-Gal-; α-Rha-; Gal-α-1,3-Gal-β-1,3-GlcNAc-β-; Gal-α-1,3-Gal-β-1,4-Glc-β-; Gal-α-1,4-Gal-β-1,3-GlcNAc-β-; Gal-α-1,3-(Fuc-α-1,2)-Gal-β-; Gal-α-1,3-(Fuc-α-1,2)-Gal-β-1,4-Glc-β-; Gal-α-1,3-Gal-β-, Gal-α-1,4-Gal-β-1,4-Glc-β-; GalNAc-β-1,3-Gal-β-1,4-Glc-β-; and Gal-α-1,4-Gal-β-1,4-GlcNAc-β-.
3 . A fusion protein comprising a fluorescent protein and SHA, a homologue thereof, or a functional fragment of the SHA or a homologue thereof, wherein the SHA protein has an amino acid sequence represented by SEQ ID NO: 25, the homologue has an amino acid sequence at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, at least 98%, or at least 99% identical to that of SEQ ID NO: 25, and wherein the fusion protein specifically binds to L-rhamnose or D-galactose.
4 . The fusion protein of claim 3 , wherein the fusion protein specifically binds to a carbohydrate that contains or terminates in a monosaccharide or an oligosaccharide selected from the group consisting of β-Gal-; α-Rha-; Gal-α-1,3-Gal-β-1,3-GlcNAc-β-; Gal-α-1,3-Gal-β-1,4-Glc-β-; Gal-α-1,4-Gal-β-1,3-GlcNAc-β-; Gal-α-1,3-(Fuc-α-1,2)-Gal-β-; Gal-α-1,3-(Fuc-α-1,2)-Gal-β-1,4-Glc-β-; Gal-α-1,3-Gal-β-, Gal-α-1,4-Gal-β-1,4-Glc-β-; GalNAc-β-1,3-Gal-β-1,4-Glc-β-; and Gal-α-1,4-Gal-β-1,4-GlcNAc-β-.
5 . The fusion protein of claim 3 , wherein the fluorescent protein includes GFP and mCherry1.
6 . A method of detecting a microbial infection caused by a microorganism expressing a carbohydrate containing L-rhamnose or D-galactose on the surface in a subject, comprising:
contacting a sample obtained from the subject with the fusion protein of claim 3 ,
detecting the fluorescence level in the sample, wherein the presence of fluorescence indicating a microbial infection.
7 . The method of claim 6 , wherein the sample includes a biopsy sample, a tissue sample, a bronchoalveolar lavage sample, a blood sample, and a urine sample.
8 . The method of claim 6 , wherein the microbial infection is caused by a bacterium or a fungus that expresses dTDP-4-dehydrorhamnose reductase gene (rmID).
9 . The method of claim 6 , wherein the microbial infection includes mycoses caused by Candida albicans, Aspergillus fumigatus , or Fusarium solani.
10 . The method of claim 6 , wherein the microbial infection is an infection by Streptococcus, Enterococcus or Lactococcus.
11 . The method of claim 6 , wherein the microbial infection is invasive pulmonary aspergillosis, and the GFP-SHA fusion protein detects the presence of fungal galactomannan.
12 . A method of detecting a cancer or tumor in a subject, comprising:
contacting a sample obtained from the subject with the fusion protein of claim 3 ,
detecting the fluorescence level in the sample, wherein the presence of fluorescence indicating the presence of the cancer or tumor,
wherein the cancer or tumor cell expresses an antigen comprising a carbohydrate capable of specifically binding to SHA, a homologue thereof, or a fragment of the SHA or a homologue thereof.
13 . The method of claim 12 , wherein the sample includes a biopsy sample, a tissue sample, a bronchoalveolar lavage sample, a blood sample, and a urine sample.
14 . The method of claim 12 , wherein the cancer is colon cancer, pancreatic ductal carcinoma, or pancreatic cancer.
15 . The method of claim 12 , wherein the antigen is a surface antigen comprising a carbohydrate containing D-galactose.
16 . A positron emission tomography (PET) probe comprising the recombinant SHA protein or a homologue thereof of claim 1 labeled with a PET isotope, or the fusion protein of claim 3 labeled with a PET isotope.
17 . A method of imaging an organ or tissue having a microbial infection caused by a microorganism expressing a carbohydrate containing L-rhamnose or D-galactose on the surface in a subject, comprising:
administering to the subject the PET probe of claim 16 , and
imaging the organ or the tissue having the microbial infection by a PET scanning of the subject.
18 . The method of claim 17 , wherein the PET probe is administered locally or systemically to the organ or the tissue.
19 . The method of claim 17 , wherein the PET probe is administered by intravenous injection.
20 . A method of imaging a solid tumor in a subject, comprising:
administering to the subject the PET probe of claim 16 , and
imaging the solid tumor by a PET scanning of the subject,
wherein the tumor cell expressing a tumor-specific antigen comprising a carbohydrate capable of specifically binding to SHA, a homologue thereof, or a fragment of the SHA or a homologue thereof.
21 . The method of claim 20 , wherein the PET probe is administered locally to the tumor.
22 . The method of claim 20 , wherein the antigen is a surface antigen comprising a carbohydrate containing D-galactose.
23 . A method of detecting the location of a microbial infection caused by a microorganism expressing a carbohydrate containing L-rhamnose or D-galactose on the surface in a subject, comprising:
administering to the subject the PET probe of claim 16 , and
detecting the location of the microbial infection by a PET scanning of the subject, wherein the presence of the PET probe indicating the location of the microbial infection.
24 . The method of claim 23 , wherein the PET probe is administered to the subject by intravenous injection.
25 . A method of detecting the location of cancer cells in a subject, comprising:
administering to the subject the PET probe of claim 16 , and
detecting the location of the cancer cells by a PET scanning of the subject, wherein the presence of the PET probe indicating the location of the cancer cells,
and wherein the cancer cells express an antigen comprising a carbohydrate capable of specifically binding to SHA, a homologue thereof, or a fragment of the SHA or a homologue thereof.
26 . The method of claim 25 , wherein the PET probe is administered to the subject by intravenous injection.
27 . The method of claim 25 , wherein the antigen is a surface antigen comprising a carbohydrate containing D-galactose.