A multidrug ABC transporter with a taste for salt.
BACKGROUND:LmrA is a multidrug ATP-binding cassette (ABC) transporter from Lactococcus lactis with no known physiological substrate, which can transport a wide range of chemotherapeutic agents and toxins from the cell. The protein can functionally replace the human homologue ABCB1 (also termed multi...
| Main Authors: | , , , , , , , , , , , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Public Library of Science (PLoS)
2009-07-01
|
| Series: | PLoS ONE |
| Online Access: | http://europepmc.org/articles/PMC2704374?pdf=render |
| _version_ | 1818031444934524928 |
|---|---|
| author | Saroj Velamakanni Calvin H F Lau Daniel A P Gutmann Henrietta Venter Nelson P Barrera Markus A Seeger Barbara Woebking Dijana Matak-Vinkovic Lekshmy Balakrishnan Yao Yao Edmond C Y U Richard A Shilling Carol V Robinson Peter Thorn Hendrik W van Veen |
| author_facet | Saroj Velamakanni Calvin H F Lau Daniel A P Gutmann Henrietta Venter Nelson P Barrera Markus A Seeger Barbara Woebking Dijana Matak-Vinkovic Lekshmy Balakrishnan Yao Yao Edmond C Y U Richard A Shilling Carol V Robinson Peter Thorn Hendrik W van Veen |
| author_sort | Saroj Velamakanni |
| collection | DOAJ |
| description | BACKGROUND:LmrA is a multidrug ATP-binding cassette (ABC) transporter from Lactococcus lactis with no known physiological substrate, which can transport a wide range of chemotherapeutic agents and toxins from the cell. The protein can functionally replace the human homologue ABCB1 (also termed multidrug resistance P-glycoprotein MDR1) in lung fibroblast cells. Even though LmrA mediates ATP-dependent transport, it can use the proton-motive force to transport substrates, such as ethidium bromide, across the membrane by a reversible, H(+)-dependent, secondary-active transport reaction. The mechanism and physiological context of this reaction are not known. METHODOLOGY/PRINCIPAL FINDINGS:We examined ion transport by LmrA in electrophysiological experiments and in transport studies using radioactive ions and fluorescent ion-selective probes. Here we show that LmrA itself can transport NaCl by a similar secondary-active mechanism as observed for ethidium bromide, by mediating apparent H(+)-Na(+)-Cl(-) symport. Remarkably, LmrA activity significantly enhances survival of high-salt adapted lactococcal cells during ionic downshift. CONCLUSIONS/SIGNIFICANCE:The observations on H(+)-Na(+)-Cl(-) co-transport substantiate earlier suggestions of H(+)-coupled transport by LmrA, and indicate a novel link between the activity of LmrA and salt stress. Our findings demonstrate the relevance of investigations into the bioenergetics of substrate translocation by ABC transporters for our understanding of fundamental mechanisms in this superfamily. This study represents the first use of electrophysiological techniques to analyze substrate transport by a purified multidrug transporter. |
| first_indexed | 2024-12-10T05:51:35Z |
| format | Article |
| id | doaj.art-e42bb463892a4ae1b64ec7df0e383346 |
| institution | Directory Open Access Journal |
| issn | 1932-6203 |
| language | English |
| last_indexed | 2024-12-10T05:51:35Z |
| publishDate | 2009-07-01 |
| publisher | Public Library of Science (PLoS) |
| record_format | Article |
| series | PLoS ONE |
| spelling | doaj.art-e42bb463892a4ae1b64ec7df0e3833462022-12-22T02:00:02ZengPublic Library of Science (PLoS)PLoS ONE1932-62032009-07-0147e613710.1371/journal.pone.0006137A multidrug ABC transporter with a taste for salt.Saroj VelamakanniCalvin H F LauDaniel A P GutmannHenrietta VenterNelson P BarreraMarkus A SeegerBarbara WoebkingDijana Matak-VinkovicLekshmy BalakrishnanYao YaoEdmond C Y URichard A ShillingCarol V RobinsonPeter ThornHendrik W van VeenBACKGROUND:LmrA is a multidrug ATP-binding cassette (ABC) transporter from Lactococcus lactis with no known physiological substrate, which can transport a wide range of chemotherapeutic agents and toxins from the cell. The protein can functionally replace the human homologue ABCB1 (also termed multidrug resistance P-glycoprotein MDR1) in lung fibroblast cells. Even though LmrA mediates ATP-dependent transport, it can use the proton-motive force to transport substrates, such as ethidium bromide, across the membrane by a reversible, H(+)-dependent, secondary-active transport reaction. The mechanism and physiological context of this reaction are not known. METHODOLOGY/PRINCIPAL FINDINGS:We examined ion transport by LmrA in electrophysiological experiments and in transport studies using radioactive ions and fluorescent ion-selective probes. Here we show that LmrA itself can transport NaCl by a similar secondary-active mechanism as observed for ethidium bromide, by mediating apparent H(+)-Na(+)-Cl(-) symport. Remarkably, LmrA activity significantly enhances survival of high-salt adapted lactococcal cells during ionic downshift. CONCLUSIONS/SIGNIFICANCE:The observations on H(+)-Na(+)-Cl(-) co-transport substantiate earlier suggestions of H(+)-coupled transport by LmrA, and indicate a novel link between the activity of LmrA and salt stress. Our findings demonstrate the relevance of investigations into the bioenergetics of substrate translocation by ABC transporters for our understanding of fundamental mechanisms in this superfamily. This study represents the first use of electrophysiological techniques to analyze substrate transport by a purified multidrug transporter.http://europepmc.org/articles/PMC2704374?pdf=render |
| spellingShingle | Saroj Velamakanni Calvin H F Lau Daniel A P Gutmann Henrietta Venter Nelson P Barrera Markus A Seeger Barbara Woebking Dijana Matak-Vinkovic Lekshmy Balakrishnan Yao Yao Edmond C Y U Richard A Shilling Carol V Robinson Peter Thorn Hendrik W van Veen A multidrug ABC transporter with a taste for salt. PLoS ONE |
| title | A multidrug ABC transporter with a taste for salt. |
| title_full | A multidrug ABC transporter with a taste for salt. |
| title_fullStr | A multidrug ABC transporter with a taste for salt. |
| title_full_unstemmed | A multidrug ABC transporter with a taste for salt. |
| title_short | A multidrug ABC transporter with a taste for salt. |
| title_sort | multidrug abc transporter with a taste for salt |
| url | http://europepmc.org/articles/PMC2704374?pdf=render |
| work_keys_str_mv | AT sarojvelamakanni amultidrugabctransporterwithatasteforsalt AT calvinhflau amultidrugabctransporterwithatasteforsalt AT danielapgutmann amultidrugabctransporterwithatasteforsalt AT henriettaventer amultidrugabctransporterwithatasteforsalt AT nelsonpbarrera amultidrugabctransporterwithatasteforsalt AT markusaseeger amultidrugabctransporterwithatasteforsalt AT barbarawoebking amultidrugabctransporterwithatasteforsalt AT dijanamatakvinkovic amultidrugabctransporterwithatasteforsalt AT lekshmybalakrishnan amultidrugabctransporterwithatasteforsalt AT yaoyao amultidrugabctransporterwithatasteforsalt AT edmondcyu amultidrugabctransporterwithatasteforsalt AT richardashilling amultidrugabctransporterwithatasteforsalt AT carolvrobinson amultidrugabctransporterwithatasteforsalt AT peterthorn amultidrugabctransporterwithatasteforsalt AT hendrikwvanveen amultidrugabctransporterwithatasteforsalt AT sarojvelamakanni multidrugabctransporterwithatasteforsalt AT calvinhflau multidrugabctransporterwithatasteforsalt AT danielapgutmann multidrugabctransporterwithatasteforsalt AT henriettaventer multidrugabctransporterwithatasteforsalt AT nelsonpbarrera multidrugabctransporterwithatasteforsalt AT markusaseeger multidrugabctransporterwithatasteforsalt AT barbarawoebking multidrugabctransporterwithatasteforsalt AT dijanamatakvinkovic multidrugabctransporterwithatasteforsalt AT lekshmybalakrishnan multidrugabctransporterwithatasteforsalt AT yaoyao multidrugabctransporterwithatasteforsalt AT edmondcyu multidrugabctransporterwithatasteforsalt AT richardashilling multidrugabctransporterwithatasteforsalt AT carolvrobinson multidrugabctransporterwithatasteforsalt AT peterthorn multidrugabctransporterwithatasteforsalt AT hendrikwvanveen multidrugabctransporterwithatasteforsalt |