Browsing by Author "Chan, Chia-Han"

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Identification of Protein Domains on Major Pilin MrkA That Affects the Mechanical Properties of Klebsiella pneumoniae Type 3 Fimbriae
(2012-05-15)
Chan, Chia-Han
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Chen, Feng-Jung
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Huang, Ying-Jung
;
Chen, Shin-Yu
;
Liu, Kuo-Liang
The Klebsiella pneumoniae type 3 fimbriae are mainly composed of MrkA pilins that assemble into a helixlike filament. This study determined the biomechanical properties of the fimbriae and analyzed 11 site-directed MrkA mutants to identify domains that are critical for the properties. Escherichia coli strains expressing type 3 fimbriae with an Ala substitution at either F34, V45, C87, G189, T196, or Y197 resulted in a significant reduction in biofilm formation. The E. coli strain expressing MrkAG189A remained capable of producing a normal number of fimbriae. Although F34A, V45A, T196A, and Y197A substitutions expressed on E. coli strains produced sparse quantities of fimbriae, no fimbriae were observed on the cells expressing MrkAC87A. Further investigations of the mechanical properties of the MrkAG189A fimbriae with optical tweezers revealed that, unlike the wild-type fimbriae, the uncoiling force for MrkAG189A fimbriae was not constant. The MrkAG189A fimbriae also exhibited a lower enthalpy in the differential scanning calorimetry analysis. Together, these findings indicate that the mutant fimbriae are less stable than the wildtype. This study has demonstrated that the C-terminal beta strands of MrkA are required for the assembly and structural stability of fimbriae.
Measurement of the adhesive force between a single Klebsiella pneumoniae type 3 fimbria and collagen IV using optical tweezers
(2006-11-10)
Chang, Bo-Jui
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Huang, Ying-Jung
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Chan, Chia-Han
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Hsu, Long
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Peng, Hwei-Ling
Type 3 fimbriae are important adhesive filaments that assist Klebsiella pneumoniae to establish an infection. Different MrkD adhesin variants on the fimbriae are known to display distinct adherence capability for the bacteria to bind extracellular matrix proteins, although the difference has not been determined physically. For this reason, the adhesive force between type 3 fimbriae and collagen IV were measured using optical tweezers. The measured force data displayed a periodic histogram thus Fourier analysis was applied to group it to extract the adhesive force of a single molecular pair. Specifically, we showed that grouping should begin with an offset at the first half of the period. Finally, we first present the adhesive force between each mrkD(V2)-, mrkD(V3)-, and mrkD(V4)-expressed fimbriae and collagen IV is 2.03, 3.79, and 2.87 pN, respectively, This result can be referred to further research on mrkD allelic effect on bacteria infection. (c) 2006 Elsevier Inc. All rights reserved.
Structural and Mechanical Properties of Klebsiella pneumoniae Type 3 Fimbriae
(2011-04-01)
Chen, Feng-Jung
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Chan, Chia-Han
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Huang, Ying-Jung
;
Liu, Kuo-Liang
;
Peng, Hwei-Ling
This study investigated the structural and mechanical properties of Klebsiella pneumoniae type 3 fimbriae, which constitute a known virulence factor for the bacterium. Transmission electron microscopy and optical tweezers were used to understand the ability of the bacterium to survive flushes. An individual K. pneumoniae type 3 fimbria exhibited a helix-like structure with a pitch of 4.1 nm and a three-phase force-extension curve. The fimbria was first nonlinearly stretched with increasing force. Then, it started to uncoil and extended several micrometers at a fixed force of 66 +/- 4 pN (n +/- 22). Finally, the extension of the fimbria shifted to the third phase, with a characteristic force of 102 +/- 9 pN (n = 14) at the inflection point. Compared with the P fimbriae and type 1 fimbriae of uropathogenic Escherichia coli, K. pneumoniae type 3 fimbriae have a larger pitch in the helix-like structure and stronger uncoiling and characteristic forces.
Uncoiling mechanism of Klebsiella pneumoniae type 3 pili measured by using optical tweezers
(2007-01-01)
Chen, Feng-Jung
;
Chan, Chia-Han
;
Liu, Kuo-Liang
;
Huang, Ying-Jung
;
Peng, Hwei-Ling
Pili are bacterial appendages that play many important roles in bacterial behaviors, physiology and interaction with hosts. Via pili, bacteria are able to adhere to, migrate onto, and colonize on host cells, mechanically. Different from the most studied type I and P type pili, which are rigid and thick with an average of 6 similar to 7 nm in diameter, type 3 pili are relatively tiny (3-5 nm in diameter) and flexible, and their biophysical properties remains unclear. By using optical tweezers, we found that the elongation processes of type 3 pili are divided into three phases: (1) elastic elongation, (2) uncoiling-elongation, and (3) intrinsic elongation, separately. Besides, the uncoiling force of the recombinant pili displayed on the surface of E. coli [pmrkABCD(VI)F] is measured 20 pN in average stronger than that of E. coli [pmrkABCD(VI)]. This suggests that pilin MrkF is involved in determining the mechanical properties of the type 3 pili.
Uncoiling mechanism of Klebsiella pneumoniae type 3 pili measured by using optical tweezers - art. no. 66441W
(2007)
Chen, Feng-Jung
;
Chan, Chia-Han
;
Liu, Kuo-Liang
;
Huang, Ying-Jung
;
Peng, Hwei-Ling
Pili are bacterial appendages that play many important roles in bacterial behaviors, physiology and interaction with hosts. Via pili, bacteria are able to adhere to, migrate onto, and colonize on host cells, mechanically. Different from the most studied type I and P type pili, which are rigid and thick with an average of 6 similar to 7 nm in diameter, type 3 pili are relatively tiny (3-5 nm in diameter) and flexible, and their biophysical properties remains unclear. By using optical tweezers, we found that the elongation processes of type 3 pili are divided into three phases: (1) elastic elongation, (2) uncoiling-elongation, and (3) intrinsic elongation, separately. Besides, the uncoiling force of the recombinant pili displayed on the surface of E. coli [pmrkABCD(VI)F] is measured 20 pN in average stronger than that of E. coli [pmrkABCD(VI)]. This suggests that pilin MrkF is involved in determining the mechanical properties of the type 3 pili.