Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Moscow, Russia, State Research Center for Applied Microbiology and Biotechnology, Obolensk, Moscow Region, 142279, Russia, Higher Chemical College of the Russian Academy of Sciences, D. I. Mendeleev University of Chemical Technology of Russia, Moscow, Russia, Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Moscow, Russia, Institute of Antimicrobial Chemotherapy, Smolensk State Medical University, Smolensk, 214019, Russia, Moscow Institute of Physics and Technology (National Research University), Dolgoprudny, Moscow Region, 141701, Russia
Aerobic gram-negative bacterium Acinetobacter baumannii has recently become one of the most relevant pathogens associated with hospital-acquired infections worldwide. A. baumannii produces a capsule around the cell, which represents a thick viscous layer of structurally variable capsular polysaccharide (CPS). The capsule protects the bacteria against unfavorable environmental factors and biological systems, including bacteriophages and host immune system. Many A. baumannii phages have structural depolymerases (tailspikes) that specifically recognize and digest bacterial CPS. In this work, we studied the interaction of tailspike proteins of four lytic depolymerase-carrying phages with A. baumannii CPS. Depolymerases of three bacteriophages (Fri1, AS12, and BS46) were identified as specific glycosidases that cleave the CPS of A. baumannii strains 28, 1432, and B05, respectively, by the hydrolytic mechanism. The gp54 depolymerase from bacteriophage AP22 was characterized as a polysaccharide lyase that cleaves the CPS of A. baumannii strain 1053 by β-elimination at hexuronic acid (ManNAcA) residues.
Cleavage of O-deacetylated CPS from A. baumannii 28 by the phage FriI depolymerase gp49. NMR data for the major nonasaccharide 4 (n=1), chemical shifts (δ, ppm) of aDQuipNAc4NAc residue at the reducing end of OS: 1H: 5.10 4.04 3.98 3.78 3.97 1.13, 13C: 92.2 54.3 75.1 58.3 68.0 17.9.
13C NMR data:
Linkage Residue C1 C2 C3 C4 C5 C6
3,4,3,3,4,2 Ac 174.9-176.1 23.3-23.9
3,4,3,3,4 aDGalpN 99.9 49.6 77.4 69.5 71.7 61.8
3,4,3,3,2 Ac 174.9-176.1 23.3-23.9
3,4,3,3 aDGalpNA 98.7-98.8 50.5 67.8 78.7-78.9 71.7 173.3
3,4,3,2 Ac 174.9-176.1 23.3-23.9
3,4,3,4 Ac 174.9-176.1 23.3-23.9
3,4,3 bDQuipN4N 102.6 56.2 77.4 58.3 72.2 17.9
3,4,3,3,4,3,3,4,2 Ac 174.9-176.1 23.3-23.9
3,4,3,3,4,3,3,4 aDGalpN 99.9 51.1 68.7 69.7 72.2 61.9
3,4,3,3,4,3,3,2 Ac 174.9-176.1 23.3-23.9
3,4,3,3,4,3,3 aDGalpNA 98.7-98.8 50.5 67.8 78.7-78.9 71.7 173.3
3,4,3,3,4,3,2 Ac 174.9-176.1 23.3-23.9
3,4,3,3,4,3,4 Ac 174.9-176.1 23.3-23.9
3,4,3,3,4,3 bDQuipN4N 102.6 56.2 77.4 58.3 72.2 17.9
3,4,2 Ac 174.9-176.1 23.3-23.9
3,4 aDGalpN 99.9 49.6 77.4 69.5 71.7 61.8
3,2 Ac 174.9-176.1 23.3-23.9
3 aDGalpNA 98.7-98.8 50.5 67.8 78.7-78.9 71.7 173.4
2 Ac 174.9-176.1 23.3-23.9
4 Ac 174.9-176.1 23.3-23.9
bDQuipN4N 95.8 57.5 77.4 58.4 72.4 17.9
1H NMR data:
Linkage Residue H1 H2 H3 H4 H5 H6
3,4,3,3,4,2 Ac - 1.94-2.09
3,4,3,3,4 aDGalpN 4.91 4.28 3.98 4.21 4.27 3.66-3.68
3,4,3,3,2 Ac - 1.94-2.09
3,4,3,3 aDGalpNA 5.22-5.23 4.23 3.93 4.42 4.29 -
3,4,3,2 Ac - 1.94-2.09
3,4,3,4 Ac - 1.94-2.09
3,4,3 bDQuipN4N 4.63 3.77 3.88 3.77 3.51 1.17
3,4,3,3,4,3,3,4,2 Ac - 1.94-2.09
3,4,3,3,4,3,3,4 aDGalpN 4.97 4.18 3.95 4.03 4.27 3.66-3.68
3,4,3,3,4,3,3,2 Ac - 1.94-2.09
3,4,3,3,4,3,3 aDGalpNA 5.22-5.23 4.23 3.93 4.42 4.29 -
3,4,3,3,4,3,2 Ac - 1.94-2.09
3,4,3,3,4,3,4 Ac - 1.94-2.09
3,4,3,3,4,3 bDQuipN4N 4.63 3.77 3.88 3.77 3.51 1.17
3,4,2 Ac - 1.94-2.09
3,4 aDGalpN 4.91 4.28 3.98 4.21 4.27 3.66-3.68
3,2 Ac - 1.94-2.09
3 aDGalpNA 5.22-5.23 4.23 3.93 4.42 4.32 -
2 Ac - 1.94-2.09
4 Ac - 1.94-2.09
bDQuipN4N 4.71 3.72 3.85 3.78 3.53 1.17
1H/13C HSQC data:
Linkage Residue C1/H1 C2/H2 C3/H3 C4/H4 C5/H5 C6/H6
3,4,3,3,4,2 Ac 23.3-23.9/1.94-2.09
3,4,3,3,4 aDGalpN 99.9/4.91 49.6/4.28 77.4/3.98 69.5/4.21 71.7/4.27 61.8/3.66-3.68
3,4,3,3,2 Ac 23.3-23.9/1.94-2.09
3,4,3,3 aDGalpNA 98.7-98.8/5.22-5.23 50.5/4.23 67.8/3.93 78.7-78.9/4.42 71.7/4.29
3,4,3,2 Ac 23.3-23.9/1.94-2.09
3,4,3,4 Ac 23.3-23.9/1.94-2.09
3,4,3 bDQuipN4N 102.6/4.63 56.2/3.77 77.4/3.88 58.3/3.77 72.2/3.51 17.9/1.17
3,4,3,3,4,3,3,4,2 Ac 23.3-23.9/1.94-2.09
3,4,3,3,4,3,3,4 aDGalpN 99.9/4.97 51.1/4.18 68.7/3.95 69.7/4.03 72.2/4.27 61.9/3.66-3.68
3,4,3,3,4,3,3,2 Ac 23.3-23.9/1.94-2.09
3,4,3,3,4,3,3 aDGalpNA 98.7-98.8/5.22-5.23 50.5/4.23 67.8/3.93 78.7-78.9/4.42 71.7/4.29
3,4,3,3,4,3,2 Ac 23.3-23.9/1.94-2.09
3,4,3,3,4,3,4 Ac 23.3-23.9/1.94-2.09
3,4,3,3,4,3 bDQuipN4N 102.6/4.63 56.2/3.77 77.4/3.88 58.3/3.77 72.2/3.51 17.9/1.17
3,4,2 Ac 23.3-23.9/1.94-2.09
3,4 aDGalpN 99.9/4.91 49.6/4.28 77.4/3.98 69.5/4.21 71.7/4.27 61.8/3.66-3.68
3,2 Ac 23.3-23.9/1.94-2.09
3 aDGalpNA 98.7-98.8/5.22-5.23 50.5/4.23 67.8/3.93 78.7-78.9/4.42 71.7/4.32
2 Ac 23.3-23.9/1.94-2.09
4 Ac 23.3-23.9/1.94-2.09
bDQuipN4N 95.8/4.71 57.5/3.72 77.4/3.85 58.4/3.78 72.4/3.53 17.9/1.17