Using wpdb->wp_query with wp_remote_post

Hi,

I am using the HTTP API wrapper function wp_remote_post on Site A to trigger a function in the functions.php file of a separate wordpress installation on Site B (two different servers).

The function on Site B triggers fine and returns values as expected. Now I wish to return information from a custom table in the wordpress database of Site B. I am currently trying to use the following in functions.php on Site B:

add_action('template_redirect', 'process_post_request');
function process_post_request(){
	if( $_POST['action'] == 'get_job_posts' ){
		global $wpdb;
		$jobs_list = $wpdb->wp_query( "SELECT job_title FROM $wpdb->wpjb_job LIMIT 5;" );
		if ( $jobs_list ){
			// do stuff with results of query here
		}
		die();
	}
}

The problem is that when it hits the line containing the query it throws an error:

Call to undefined method wpdb::wp_query()

Why isnt this query call being recognised? What am I missing?

Any insight much appreciated.